Would it benefit me to take a crack at the DLAB, even if my #1 choice does not require me to go to DLI?

If your recruiter lets you take it, why not? It’s like a condom...I’d rather have it and not need it, than need it and not have it.

As an adult, stuff like the Rosetta Stone is great...if you don’t want to be fluent in a language. Unfortunately, the only way to attain fluency is immersion, and closest thing to immersion (other than moving abroad) is DLI.
The school is hard, for sure, but taking a DLAB now can’t hurt you

DLI is the most intense language training course you will ever take, Rosetta Stone has nothing on DLI. You are completely immersed in the langauge and the culture and best part is they pay you to go to class and learn a langauge. I would recommend DLAB(although it doesn’t really tell you if you are capable of learning a langauge) and try your shot at getting into langauge training

Sir, my advice to you would be this, take it if you feel that it can enhance your career opportunities, but only take it if you are seriously prepared. There are many language opportunities beyond DLI that require a DLAB rating. Doing well on the DLAB can open or close the door on these opportunities. I can't speak for the Navy, but when I took the DLAB Army policy was that if you failed you could take the test again in six months but if you earn a passing score, any passing score, the the rating you earned was the one you were stuck with. Retaking the DLAB after receiving a passing score required the endorsement of a general officer. This is to say, if you have ambitions of ever learning a more challenging language you could easily sabotage yourself by going in unprepared and passing with a score that is too low. One last thing, if you choose to take it, stay cool. I was convinced that I was failing the test through the whole first section but upon receiving my score I was extremely pleased.