Phil, there are a lot of comparisons between the Futura and Carve on the Starboard Forums, so have a look there. Here's one
http://www.star-board-windsurfing.com/forum/showthread.php?t=15981&highlight=carve The 2011 Futura 111 had a narrower tail than the latter models, yours would be a little better in the chop compared to the current models IMHO.
One of the sailors here does have a Futura 111 and a Carve 111, he said that the Carve planes up a little slower, but is better in the chop, gybes better and probably as quick as the Futura off the wind. Pretty sure it wouldn't be quite as good upwind.
I have had a Futura 111 2012 model since new and love it, just keeps getting better and better. I am just looking at getting a FSW around 100 litres as well to bridge the gap to a smaller wave board. If there was a smaller carve, I'd certainly look at getting one, I thought I heard that they may be bringing out some smaller models. Hope that helps mate.