Mathew...honestly, if you use an airplane-grade aluminum Reo of what ever size, it's virtually indestructible. If you drop it on cement from two stories up it MIGHT dent the body a little but it will still perform flawlessly as a the battery, juice bottle and other pertinent parts are inside. What might and probably will break from a hard throw or a long drop would be the atomizer attached to the top of the Reo.
I can't address your concerns about carrying it in a shirt pocket, but just from using a Reo I can assure you that it'd very very difficult for the juice bottle to get squeezed unless the owner is deliberately squeezing it So it'd be unneccessary to put the door in upside down, tho i just tried it and it can be done, but you simply don't have to go to all that trouble because the juice bottle won't leak The most that would happen, if you inadvertently pushed on the bottle is that a very little juice would go up into the attached atomizer but it wouldn't leak out unless you took the whole unit out of your pocket and turned it upside down. .I think you can easily carry a Reo mini.2 in the pocket with your wallet and gerber. Reos aren't long, they're square in shape, so there'd be no bending of it.
The only "weak point" on a Reo could be the atomizer on top of it, if the whole unit is dropped either from a great distance or with some force. The Reo survives virtually unscathed!
Please excuse some of us that you feel offended you...us Reo owners and redeyedancer's fan base can get a little uptight when the Reo is questioned or someone comes along that asks if it can be improved upon.
Please, if you don't leave all together, and have a little time whenever you have it, read some of the various threads here on the Reo forum, it'll give you a much larger scope of all things Reo.