I think it's always nice to have a back pocket; however, I rarely touch it because I try not to stretch it. For the lining, I don't mind it being leather or not since I see outside of the bag most of time not the interior.
Do you have something else in mind already? If so, maybe you should go for it instead of this flap bag.
Hope that helps.
Thanks for the advice! I have jumbos and a WOC. I'm looking for a medium size bag with a crossbody option. Reissue would be perfect but I'm not a fan of the vintage look to it. It sounds like I should go for classic m/l and compromise on the chain length.