I'm also worried about the seat I'm sitting on, mainly leather car seats. If I get into someone else's car and they have leather seats, I couldn't ever forgive myself for making any kind of mark. I could just move it to my front pocket at that time, but if I'm going to move it sometimes, why not keep it in the front pocket all the time? Also, the back problems thing. Also, sometimes I carry a small traditional which is a pain to find in a deep back pocket and might be too "fragile".
I don't understand back pocket carry at all really. There are so many negatives to it and what are the positives? You keep the side of your front pocket free? For what, your hand? I could see doing it if you have a large tactical folder and you front pocket carry a small handgun, but that's about it
I have been known to back pocket carry a Buck 110, but that thing is full brass, heavy as a beast, no pocket clip, and carries awkwardly sideways in the front pocket. Of course, once I sit down somewhere I take it out of the back pocket.
Let me ask you, if there were a 4" folder in a chair you were about to sit in, would you move it before you sat down or would you sit on it?