I know you said Summits but as a lowly Ascent member I would like to chime in. I love the priority check-in and priority security. Prority check-in saved me a ton of time in MCO recently (probably 45 minutes), though I do feel guilty at times walking right up to the counter. Priority security at MCO left stuff to be desired still had to wait in the first half of the line. Though I guess if I hit a time where the 2nd half of the line was long it would be a good feature too. Have to wait till check-in for my stretch seating but for the most part I've gotten a free Y+ seat.