Ours may actually be a 2" topper (I don't remember). Either way, it is as comfy as I've described.
As far as rolling it up: That is how it was when we purchased it, so that is what we continued to do when it was not on the bed. When rolled up, it takes up half the couch, but we've had no problem with it staying there during transport.
Here is a picture of our front bunk with the foam mattress, mattress pad and sheets. The only thing(s) missing are the sleeping bags.
Because it is usually just the dogs and us, we do not put the foam on the other bunks. On the rare occasion that we have visitors, they sleep on the mattress with just sleeping bags. No complaints yet, however.