The Atlantis is more of a clearomizer than an RTA. Not saying it's not good, just that I don't think many would consider it an RTA.
I've been having good luck lately with my Aqua V2 - but nowhere near 50 watts. On a dual coil I usually run it around 20 - after that, it can't keep up however I build it. As you point out, it's mainly an airflow issue.
The RTA section of the subtank is surprisingly good too - I didn't think those liquid channels were deep enough, but it works excellently at 15-25 watts. I can run it at 30 because of the improved airflow on it, but I actually prefer it a little cooler.
I haven't found an RTA that can consistently be pushed to higher wattages and honestly, I don't think I am looking for one particularly. I think I sometimes like the tighter draw, the mouth to lungs and the improvement in flavor (and battery life) of running them at lower wattages.
But I do agree, I think we will see some serious innovation in RTA's with much better airflow and e-liquid feeding allowing wattages to be pushed far past where they are now.
Just as an aside, I didn't ever foresee me buying and using (and enjoying) a clearomizer again, I am enjoying the innovation in the vaping industry and I look forward to seeing further improvements to the equipment we use in 2015.