Hey peahead,
I recently purchased a 23' Bertram after months of searching and contemplating between the 23 and 25.
It came down to two things for me - cost and maintenence.
There are a few 25s around under $40k but are usually older with original engines. Be wary as you could be up for reconditioning or new legs etc which is more money and also osmosis as was mentioned.
25 is definately a larger boat with almost 2 foot additional beam. This comes at the price of two motors taking up more space too though!
EIther way, you are buying a well known make with excellent sea abilities. If you have any q's, feel free to post or PM me.
-Dave.