The Ariel looks like an improvement on the NX2, but based upon my experience with the NX2 it would be a good idea to wait at least a year before purchasing. The first version of the NX2 had some kinks which were addressed in the second version and I'm sure this will happen with the Ariel. It seems that some problems come to light only after hundreds of pool owners with varying pool conditions, styles, configurations, etc. have these things running in "real world" conditions.
The Ariel clearly addresses some of the problems on the NX2. For instance, on both models of the NX2 that we have, the plastic has hairline cracks around the 4 corner wheel areas which are probably caused by the way the thing "slams" into the walls on a fairly consistent basis. The wheels are the first thing to hit, and sometimes it hits quite forcefully. I'm sure this is the reason that they've done the redesign without the protruding wheels and why they've incorporated sensors to avoid obstacles.
On the bright side, our initial NX2 is still working great after 5 years. We keep it in the pool 24/7 from June through September.
I WOULD NOT LIVE WITHOUT ONE OF THESE THINGS IN OUR POOL.
