You can only use a carto or tube-style atty on a Roughstack because of the switch being so close to the 510 connector. However, if you get a short 510-510 extension, you can put ANY device on it, from a carto tank to a Vivi Nova, to a Genny.
I just got a RoughStack Shorty, and with a short extension, I am currently running a Kanger MT-3 on it with no problem at all. And I tried my IBTanked Carto tank on it, and with the extension, it works just fine (and looks pretty awesome!)
The Roughstack is built like a tank, and the switch is easily replaceable. If you are looking for an inexpensive top-button mechanical, I would recommend it whole-heartedly. They seem to be VERY rugged. Not particularly a sexy mod, but they are simple, reliable, and solid.