For your second cook I think you should be pretty proud! They look tasty to me and that plate looks like July! I’m with the leave the membrane crowd. I never bother removing it. Keep at it and posting!
I use a SNS, went for 250 for 3ish hours then wrapped and raised to 275-300
Got it from a market, very tasty!U
I'd think the reason you thought your ribs were a little tough would be that they weren't quite cooked enough. Membrane or not won't make a world of difference if they are cooked enough. Let them go a little more time, 45 minutes to and hour, track the cook like I advised earlier, and soon you'll be as happy as a pig in mud! Nice thing about this hobby is that you can eat the mistakes, and they still taste pretty darned good. You make that tater salad or buy it at the market? Just wondering. RAY