I don't have any experience on the Futura 144, but I have sailed the Futura 133 and found it to be very much like a Carve 133, only faster, easier to jibe, and slightly earlier planing, so I think you will really like the Futura 144.
It should be a little faster on the top end and turn and jibe significantly better than your Carve 151.
The planing thresholds would be similar, with maybe a slight advantage to the C-151.
As far as how well the Futura 144 will slog, that's going to depend quite a bit on your weight. If your really need the extra 7 liters of volume, then it will matter, but if you weigh < 200 lbs. (90 Kg.) then I see no problem with the reduced volume.
If you are heavier, you can probably adjust to the slight difference in volume quite easily.
Hope this helps,