Years ago (before they had the really nice trainers and computer hookups and the like) I had a great set or rollers. The drums were larger than that they make not, but the ting I really liked was that only the tops of the rollers were exposed and there was a platform to stand up to get on the bike. So many of them now are all open and the hardest part is getting on the bike because it is a lot higher up than when you are on the road, and there really is no comfortable place to stand. With my old set yo could not fold them up, but I was not transporting them anyplace.
I had a set for a while, but I just didn't like clipping in and out six inches off the ground. If I could find some like my old ones (that I stupidly gave away years ago when I quit racing), I'd jump on them but the trainer is fine for what I want.

The parabolic roller do keep you more centered when riding.