In short, yes, the numbers are skewed a bit high, but the caster is putting himself/herself at a greater than normal risk. It would be silly if the caster uses this spell while still standing behind his or her comrades. If so, it would be relatively easy to distinguish the true from the false. No, the only practicle application involves standing virtually toe to toe with the foe to be copied, and that's not something most casters are immediately comfortable with, having so few hit points and crappy armour class and all. Hence, the 10 foot range.