Is the current rating scheme of rater, senior rater, and reviewer painting the best picture of our NCOs performance and potential?

I understand your train of thought with the question. First, as a rater, I constant/daily interaction with the individuals I have rated. Observing their leadership capabilities/MOS proficiency, etc. has never been an issue. I would definitely say the same being rated by both Commanders I have worked with/for. A respectable rater should make time to counsel, observe the individuals they are rating, and periodically give them feedback (through counselings). It is extremely unfortunate when this doesn't happen, and I have witnessed that before.
Regarding evaluations by subordinates... first, which subordinates would you include in the evaluation? Can you trust that these subordinates would take a professional approach, leaving personal prejudices out of the equation? Do the subordinates have the maturity level to offer a professional opinion on leadership evaluation, mentorship, etc.? Peer evaluations are common in schools, and the aforementioned issues are always present. While I think these are helpful in determining the "climate" of the company, platoon, squad, etc., I do not think that subordinates should have an active role in the actual rating system. I could see it getting very messy.

No it isn't that is why it has been changed. Look for an article I am writing in the Command Post to help explain it.

I hope so. I have been out of the net (retired) and not privy to the new and improved rating schemes these days. I would be for a subordinate having input as far as my performance. This would help distinguish an NCOs performance more accuratley instead of the good old boy system of inflated NCOERs.