I have not sailed the 2012 Carve 131, but I can give you a fairly good comparison between the 2011 Futura 121 and the 2011 Carve 111.
Both are pretty fast, with the sail range you specify.
The Carve is very slightly easier to jibe and a bit more "turny", but the Futura is slightly faster on the top end, but still quite easy to jibe.
I do not think you can go wrong with either of these boards to replace your 2004 Carve.
Both of the newer boards will be a little faster, and both with be as easy (if not easier) to jibe.
The Carve 131 is going to seem a little larger than your 2004 Carve (what size is your 2004 Carve as it's important to compare one size to a similar size.)?
The Futura will be pretty much as easy to sail as your 2004 Carve. The Futura line borrows some design
items from the iSonic slalom race boards, but blends those design items into something that's nearly as fast, but much more user friendly.
Hope this helps,