Neither of my Curlies care weather it is a step up or ramp. The ramp they are more catious stepping up but that's about all. I have found that some other horses are nervous about stepping on the ramp because they are not sure what it is.
I have also read articles that the ramps are dangerous because you lean down to put it up and then a horse could possibly kick you if they wanted. The step ups have been known to trash horses ankles when they try to back out too fast. But, for me, it doesnt really matter. As long as my horses are comfortable in both it doesnt matter to me.
Shaneequah, 1998 gaited Bashkir CurlyxArab mare
Johnny Cash, 2001 Arab x pony gelding
Brighty, 2013 Standard Donkey jack