I've been looking at mechs too.
The fire buttons are usually on the very bottom or bottom side. It seems like this would be awkward to use. Is it?
Back in the mists of time I had a Mako and a Megalodon. Both had bottom buttons and both worked very well - not awkward at all.
However I wouldn't go back to a mech unless I was going to try sub-ohm, which I don't feel like doing. I value the safety features and flexibility of my Vamo.