Should I opt in to BRS or stay legacy with 11 years in?

You're outside of the window where there's even a comparison between the two. Stay in the Legacy plan.

Keep doing what you're doing, and put as much as possible in your TSP. If you can, put 10% or more and make sure it's not in the G fund.

I would recommend reading about the TSP funds and how they compare to the larger funds that they're supposed to mimic.

If you don't want to read or play around with it, then move your money to the most appropriate L fund for the year you plan on retiring.

Your pension is guaranteed, for lack of a better term. Your investment is not.

Also, my two cents on a Financial Advisor. I have a BBA in Finance from the University of Wisconsin, and I manage my Mothers trust for retirement, so I am also a trustee making investment decisions quarterly. Anyways, my advice to anyone in the Military is this. Trust nobody 100% that says they are a financial advisor........trust has to be earned over time and across at least one bad downturn. Lots and lots of crappy people in that field and I have hit more than my fair share. Learn how to invest for retirement on your own. It is not rocket science, it will not take more than 15-20 min of your time each day and the payoff to you is you get to earn a larger nest egg. So spend $15-25 and subscribe to Kiplingers Personal Finance Magazine. Read it monthly specifically learn from their recommended stock picks what they are looking at in each company. Try some investing on your own with make believe money. Track your returns. Take a stock investing course at a local community college if you have time.......it will be the best time and money you ever spent in your life. You can learn how to do this over time with experience, it is really very easy after you get some experience. Also, everyone gets burned at least once in this game......nothing can stop that. So be prepared when it happens but think long term and that is where tracking your gains helps. Are you gaining more over time than your losing? Are your returns usually above the Stock index funds? If the answer is yes to both questions than who cares about the lost money. Even Warren Buffet losses billions every once in a while. His gains far exceed his losses, so it does not matter.

You should punch your info into the BRS Comparison calculator.

Personally, I would stay legacy. The strength of the BRS is the matching in the TSP and you've missed out on 11 years of matching.
The matching is slightly more complex than a 1 for 1 match. Off the top of my head, you contribute 5%, they match 3.5% plus an automatic 1% and there's another 0.5% in there somewhere that totals 10%.
As for the G fund, you're not actually supposed to put your money there, that's just the default. There is an L fund that distributes your funds according to risk based on your projected retirement date and automatically adjust them as you age.

If you are not eligible for continuation pay, then you aren't eligible for BRS, at least for the Army. It gets more complicated if you are prior service. The mark for CP and BRS eligibility is 12 years. If you have prior service, the 12 years for BRS eligibility is based off your PEBD, not your BASD.

There's no reason to expect you'll get kicked out. There is no two time non select for enlisted like officers deal with. You could spend 14 years as a mediocre SSG and still retire as long as you don't get in trouble.

It's a tough decision, but one that should be considered with a Financial Advisor or Financial Planner just due to your circumstances and situation. One of my colleagues actually did a very informational webinar regarding the new BRS system. There is a lot of great information in it. My colleague who presented this, actually worked on it before he retired out of the service. I hope this is helpful!
The Blended Retirement System Explained: Should You Opt in?
https://www.aafmaa.com/Newsroom/Webinars

CW2 (Join to see) Use the BRS calculator but you really should stay in the legacy system unless you know you can't make 20 years. If you have made it this far, you will be thousands of dollars a month better in legacy.
Regarding finances, sadly much of the industry is designed to take a significant cut of your investment for them to exist or they are ethically challenged, they put their interests in front of yours.
Even USAA, which I have a tremendous amount of respect for does not act as a fiduciary in every situation. I like the USAA foundation, it offers solid advice, you can call into USAA and see if they will assist you in determining the calculations.
If you feel you need someone to help you invest, that is fine, just be prepared to pay for the advice and ask for the fees and disclosures up front.
John Bogle, the man behind the now, Trillion dollar industry of passive index investing has inspired others. They offer free advice that has beaten the majority of managed money for over 50 years.
https://www.bogleheads.org

I am at 12 years in and will be staying with the current retirement. My opinion is that it is great for those who have 6 years or less TIS, 7-10 really need to use the calculator and a financial planner, above 10, stay legacy.

Sure, calculate away. Problem is your behavior will be the determinator. Many get a result of more money if you stay legacy, presumably living to a ripe age. Problem is humans have a habit of blowing away money fairly quickly. You can easily have much more at 60 if you invest your 20 year retirement vs. going Blended. Problem is people don't do that. So when you hit the age where you can't or don't want to work anymore, the monthly income with legacy is less. That's when you need real money the most So if you have discipline, Legacy can work best. If you aren't disciplined enough, then Blended may be the way to go. Oh, college for kids? If you weren't disciplined to put in a Tuition Program when they were born, that's an indicator of not disciplined enough. Not putting 5% or better into TSP? Not disciplined enough. Run the numbers of what you will do, not what you'd like to do. A financial advisor can give you a good read on options, but it takes discipline to stick to the option you choose. Either way can work well if you stick to the plan.

I would spend a little bit of change and speak to a true financial planner instead of fishing in the barracks planner pool. It’s your money, so the most to make it work for you.

I think to answer that you’d have to chart out which policy gives you the best return. I know this, if the new policy was opened up to Veterans would that opt in if allowed? I sure wouldn’t.

I'd stay legacy. The new one was for folks not getting their 20. Even if active duty were to kick you out try the Reserves both part time as well as full time can still get you to 20 plus. Another benefit is that it gives you an automatic network looking for work if you go into the reserves. As long as you make your 20 you'll get paid monthly the rest of your life delayed if reserved but still a good investment. Go out and look for that civilian job that pays well, use it to add to your post mid 60s final retirement plan. Good luck!