Thanks Kuang, for giving me the opportunity to rave about my brand new Atomic M1 (even though this begins anew the same thread that's been rehashed ad infinitum on the board). After much research here and in the trades, I settled on the Scubapro MK25/S600 combination and the Atomic M1 as the finalists (though Apeks and Aqualung, among others, apparently rank highly among divers).
After trying out the Scubapro, decided to go for the M1 and, I've got to say, it's amazing so far...Breathes absolutely without effort, including on a 120-foot wreck dive in horrible conditions, featuring a 3 to 4 knot current which did not in the least disturb the purge on the 2nd stage.
It's light, it's compact, it's impeccably machined and assembled and it even *looks* cool! Of course the price tag is golliath, but, so far, looks like it's going to be a worthwhile investment. (see my previous post asking for M1 advice)
Happy choosing....
ps...Foregoing maintenance does not void the M1's warranty and that maintenance is only scheduled for every 2nd year.