I have a cuboid, and it is my go-to device.  I mainly use three devices now.  The releaux is my heavy hitter, but it stays at home for obvious reasons.  The cuboid I take out and about.  It's been my main device.  I haven't heard of the shallow 510 issue,and I don't seem to have any problems with my atomizers.. I mainly use goblin mini clones, and they have no problem.  Besides, if it did have a small gap, that just means that the heat won't transfer to the mod, and it won't scratch it up as much.  I do use Kepler type fins on all my mods though, so that could also be an issue.
The last, I seem to be using more and more, is the Cloupor mini 50w.  it fits real nice in the pocket, and is shorter.. with the atomizer... than a 12 oz can of soda.... something to be impressed with.  of course, that is only a single battery mod.
All three have been reliable with absolutely no issues.