I got no experience with that kind but the Tunze is by far the only ato I would buy. I've had mine for a good 5-6 years and so far has not failed me at all.
Seeing something at a trade show prominently displayed, talked up by manufacturer reps and saying it looks nice is a lot different than really world experience of fellow reefers who have used a product for years and years without issue. I seen a bunch of issues on RC and YouTube with those Autoaqua ATOs.
I have the standard Smart ATO and it is an amazing product. I cant believe they made it even smaller! I have my mine on a 20g fusion for a couple years now and would definitely recommend!!
Spectrapure ATO, been running for about 5 years now. Uses a pressure sensor instead of a float switch. I have the pump in the stand (1st floor) and it pulls from a brute can in the basement
Have the tunze osmolator top off since 2011 without any issues. I think the Tunze osmolator is one of the most reliable top off systems .
Having said that, I have seen the Smart top off at a.friend house, it is very nice and much smaller than the tunze. Not sure how good and how reliable they are.
I have the standard Smart ATO one and would take it over any other ATO product any day. I've been using mine with zero complaints for nearly 2 years now. I'd imagine the micro is equally great. I've owned Eshopps and Tunze ATOs as well. Eshopps ATO I hated (float valve, not a fan) and the tunze one was definitely great and all, but I feel this one is far more reliable and a fraction of the price. I'd say go for it. Get it from a site online that has free returns if you're concerned.