Mosfet adds an electronic component to a simple circuit/mechanical system, if you're concerned with durability, this is a consideration. I don't have the box you refer to, but do have a Tesla Invader II with essentially the same circuit path, and have not had a lick of problems with it under normal (not hard use) conditions.
If your primary concern is durability, I'd be thinking pure mech. Either the Raptor or Bigfoot will be tough to improve upon. I run VTC5's in my Raptor, and chain vaping all day long on one pair is no problem. The screw in batt fasteners are in my opinion much more secure than the magnetic sliding door, and only an minor inconvenience once a day. The spring switch in the Raptor is a good solid flush mount, short throw switch. The Raptor is chunky for it's size, but keep in mind it's basically a solid block of aluminum with two battery size holes milled into it. Don't sweat the Delrin top. That stuff is very resistant to impact.
For a tough, take it to work and bash the heck out of it mod, honestly, I'd get the Raptor. For lowest price and fastest shipping, find a stateside eBayer with lots of good feedback.
