My current daily workhorse is a Kbox with a Subtank mini, and I'm really keen on that RBA/RTA (why do they call it an RBA, isn't it an RTA?) attachment, lets me control just another aspect of it. I like me some control. I've been on the look out for a nice, sturdy DNA-or-the-like device but I've got a list of features it's gotta have and I haven't been able to find one that checked off all the right boxes yet. (for instance, I need-need-need to have a secured battery, as I hike and camp a lot, so magnets holding the battery bay closed just isn't going to cut it - threaded, secure battery bays are a must). If I'm giving the Sub a break, I'll crack out the ol' Magma what with my dual twisted blahblahblah ... never gonna quit loving that Magma. (threaded top cap was and still is my favorite feature of it)
Haven't touched my collection of mechanicals in, dang, a long time now. Probably a nice layer of dust on 'em by now.
But I hear you on the Kayfun-love, getting into rebuildable tanks was a big ol' "a-hah!" moment for me. Best of both worlds.