I know this is an old posting, but certainly a valid question.
I too own a 250 which I will be dropping into a retrofit. Here is Larry's response to the question:
The bottom 2 are step multiplier same as V200. the top one isn't used.
The drive only has 1 bank.( not 3 like older V200F)
Just an FYI for those who will be purchasing this product in the future.
Mark