The overall flex - when you have the springs out and supported on jacks, see how it flexes without any springs at all. You should be able to see what's limiting it. If that's not enough for you, then you'll need to go with a long arm suspension.
Short arms don't flex near as much as longs. Either type binds due to holding the axle in 4 places, just the LA's don't bind as soon.
I don't like the anti-rock bars - they are just somewhere between stock and nothing. Stock gives you control, then when off road I totally disconnect it. Sure it's a PITA, so is adjusting the shocks for street or trail, and adjusting tire pressures, but it's worth it.
Did it also relocate the rear trackbar?