Am I crazy that I thought the deck was fairly roomy for an RTA? You could easily use 3mm coils. The only part I thought was tiny were the post holes and screws, but even those were pretty much the norm on a 4 post tank.
I'm tootling mine right now as I wanted to know if it was tootle friendly, and its working great. My next build will be dual coil, and will probably go on a mech as I'm going to need the mod its on for a single coil tootle tank (although I often build those for mechs, too).
I'm not qualified to call anyone crazy but compared to the Kayfuns, Taifuns and other single coil decks I would call the GMini cramped or claustrophobic then the Bellus with Velocity or Magma like deck you could run 1-4 coils easily