I just went from K-Rads to Holy Rollers about a week ago. The Holy Rollers are wider by about .5-1", they're a fair bit taller, and they have more consistent casings. The K-Rads have a floppy sidewall with a stiff top, but the Holy Rollers have a pretty thick casing all the way through.
The grip is much better on street and hardpack, but I've found they give out kinda suddenly. Where as the K-Rads always kinda slide around and make noise. I'm really glad I went to the Holy Rollers.