You'll lose some velocity (not much)...but gain a stiffer barrel and lighter gun.

So the 24" will be:
Slower velocities (don't hold me to it, but I'm thinking about 50fps per inch)
Lighter
A little more recoil due to reduced weight
Stiffer barrel---which means it may be more accurate.

To me, the performance would break even...fair trade, FPS for stiffer barrel. So if velocity is the only reason you're questioning cutting it down I'd say go for it.