I have a Summit, and after using it for over a year, there are reasons to dislike it. However, there are a few things it flat out does better than any traditional press.
I have it set up for BHN testing (LEE) my cast bullets, and can't see any other press working as well. Where it really shines is for bullet seating, the feel and precision are superb. It can also be converted to an arbor press, a feature not easily duplicated by a traditional press. One operation it does not excel in is FL resizing, IMO a deficiency of design.
Another niche is the top of the bench mounting, great for a stand at short depth reloading bench.
My stand at bench is a bit deep, I think a 16 in deep bench would be ideal, great for a restricted space reloading room.
Spent primer handling isn't it's strong point either, I find that any press with a hollow ram and a clear plastic hose out the bottom is perfect. Redding and LEE have it, and IMO they all should. If I de-prime in a single operation, my Ultra-Mag gets the nod.
I prefer a press that has a toggle linkage, most have, LEE does not. LEE builds a stop into the linkage, to prevent toggle, or cam over. I can see advantages to either design, but prefer the toggle over. If I were to buy a LEE, I think I'd remove the stops and try it that way.
If I were forced to own just one press, the Summit wouldn't be the one, however, if I were allowed 3, it would be one of the three. #1 would be a strong O frame, #2 would be a easy to use turret, and #3 would be the Summit. If case forming were in the mix, hard not to like the Redding Ultra-Mag. The U-M would be the perfect press if it wasn't for the front only access, I like to feed with my left hand and operate the handle with my right.