We looked at them (the slide-on one) when we were looking for a slide-on a few years ago. I hated it, can't put my finger on why. It just didn't feel good somehow, things didn't seem to be in the right places or something. Also that big mechanical "knee" beside the stairs - I bashed myself on it when I went up and down the stairs. I've noticed since that they've got a big padded cover to put over it so it must have been an issue with other people too - one more thing to pack and unpack and take up space.
The other thing we both didn't like was the remote control opening and closing - something else to go wrong and it shouldn't be necessary, ours is manual and easy as pie for one person because it's properly balanced and sprung.
I've never met anyone on the road who has one, so don't know what others think of them. That was just my impression as an interested prospect. I've looked at them just out of curiosity at camping shows since, and still glad we didn't buy one.