Acrobatx is definitely tricker, better with flat spins and advanced "slack line" stuff, but I got more broken spars and a smaller wind range with it.
But, the Techno offers better lift in light winds, is quite a bit tougher, and offers better over all stability.
I like both, but if I'm looking to learn slack line tricks, the Techno won't take me far enough.
Click here for excellent tutorial examples of "slack line" tricks by Randy Greenway.
If you don't mind it a little smaller, try the Jump by Level One for about $100... A little bit better full size kite, for $160 is the Silver Fox STD.
Those are currently my top picks at those two price points.