I know you stated that you have reason NOT to upgrade at the moment....but I would think it would be a better deal to upgrade even if you don't install X3...JMO. Then again, you could install X3 along side of X1 and use both if you wanted.
I have the Fairfax kit and the Jazz kits (brushes and sticks) and they sound really good. Then again...the kits that come with AD2 sound good also. I really can't say that they sound "better" than my Superior Drummer sets...I also have the Jazz sticks and brushes. Both products have great sounding drums.
I just think you'd be better of money wise to do the upgrade and get AD2 for free. But like I said...just MHO.