I think the Tesla has a better menu system than the Z-Max. It also has a feature that I haven't seen in any other mod, (certainly not in the same price range); a spring-loaded center pin. Regarding the button placement, I think they're in the right spot, otherwise you'd be hitting the adjustment buttons with your index finger while pressing the fire button with your thumb. Most people just seem to notice that they're above the screen and jump to the conclusion that it's "wrong", without thinking about how they'd actually hold and use the unit.
the tesla looks like it was designed by 10 yr old boy who just finished watching star wars IMHO