I have a summit open shot with the stirrups. I like them much better than the straps that were on my old stand. I can secure my feet in them without even looking. With the straps you either have to secure yourself with your safety harness to use both hands or do it with one hand.
If you do get them make sure you use a good bungy strap across the back of your feet. After awhile they will weaken, and not hold the stand as well as it did before.
I was like you... "why change something that ain't broke?" After somebody stole my summit climber, I purchased a new one with the stirrups. Man, It's way better! No bending over straining to get your feet in the straps making all that extra noise, just slide your feet under them and go.
I'm with everyone else. This will be my 4th year with my Viper and I LOVE the stirrups. Best treestand invention since the climbing stand! I used to hate fumbling around with the straps on my API. No more...awesome. Some places have poles in the store where you can actually try the stands. I know Kinsey's does, or did anyway. Not sure now that they rearranged everything down there.