I've owned a T2 (not X) for about 2 years now. It breathes effortlessly in any position I've ever found myself in. Upside down, inverted etc. (I do that quite a bit looking in holes etc.) It's also completely dry in every position. It is one of the most expensive out there and you can get the same performance for less in both the Atomic and other lines. I would point out that the Scubapro Mk25T/S600T is just about the same price.
Actually the major difference across the Atomic line is the materials used and swivel options, the Z2 breathes the same as the T2.
What I really like about the T2 is that the 2nd stage is very light. Add in the swivel and it's zero jaw fatigue. The swivel turret on the 1st stage is another nice feature, it makes routing hoses easy. Mine all lay nice and flat along the top of my BC. I fly everywhere I dive and carry the reg onboard so the small weight savings is a minor help also. I also just had my first 2year service done, parts are free lifetime but I still had to pay $60 for labor. So that's a cost to factor in also.
I dropped my entire rig off the tailgate of a truck and it inverted and landed on the 1st stage. Although the top of the tank valve body took some of the impact, I just dusted it off and went diving - for the next year. Titanium is pretty strong stuff.
Some people will claim that Ti is inherently dangerous with Nitrox. Atomic only claims compatibility to 40%. But I've never been on a dive/boat where anyone was diving above 36%. I would think the tec divers who are use Dive-rite or Poseidon regs anyway.
