Having owned both sleds and logged many miles on them I offer you this opinion:
SRX will corner and accelerate better than the SXr, the top end pull Is addicting.
The SRX will hand your A@# to you in the giant bumps but flies straight and true in the moguls, The SXr will be better in the Giant stuff with more travel both in the front and rear and is pure comfort in the moguls.
The SRX runs on Premium fuel, the SXr " if not tweaked " will run on Regular fuel.
When modified the SXr will run close to a stock SRX. A Modified SRX will be hard to beat regardless of make or modification of the compitition.
Lake racer / Trail sled = SRX.
Big mile trail sled / play toy = SXr.
I wish I could afford to keep both in my fleet.
There are many more items to compare between the two sleds and even more modifications avaliable, all are up to the driver and what he wants the sled to do. Good luck with your decision and by the way they are both great sleds. SpartaSXr