I put a Bond Arms 45LC/410 in the car with PDX1 410 shells as a back up.
I usually carry either a Glock 20sf, 29sf or Delta Elite (not often on that one) so I guess I qualify as carrying an odd caliber. But, I think 10mm has a bit of a following and would not classify it as too odd. Then again, they don't carry 10mm ammo at Meijer's, so maybe it is odd after all.