I have used all 3 and like the elites the most. I feel that they offer more support and shock absorption for my competition horses that I use for barrels and working cattle. I will occasionally reach for my Pegasus if I'm only planning on doing slow flat work as they tend to help the legs stay cooler but they feel so flimsy that I just don't trust them for fast runs when my horse is really working hard. The classic equines have been collecting dust for awhile now because they are really flimsy and let in tons of sand and dirt, they also have a lot of stretch to them so its easier to get uneven pressure when putting them on and they can also be a little bulky...
Not sure what you mean by the little pad? I always use back boots no matter what, if I'm going to take the time to protect the front legs why wouldn't I protect the back legs as well. I always use elites on the hind legs, never tried the Pegasus as back boots. Iconoclast is another good boot that I think are even better than the Elites... you may check those out as well.
I have both the Elites and the Pegasus, without the little pad thingy.....haven't seen that before. I like the ease of the Pegasus, and will use them when we are not really working hard at all, but agree that the SMB's have more support...and, in fact, I got the Pegasus while my guy was in training, and the trainer (one of the top reining trainers) agreed. I only use fronts, since I use leather skids on the rears, if anything.
The elites have a more contoured fit so they are not as bulky and they fit around the fetlock area a lot better. I have had both the smb II's and III's in the past and wouldn't go back. They also let more dirt in.