I sometimes did ukemi on hard sufaces. For a while I just liked doing that to show my friends what i could do (very childish, i know). I also used to try that in the basketball gym in the school I worked in at the time.
I can't remember having any problem in those circumstances.
However I did have to take ukemi twice on the road, both times when falling from my bicicle. The first time everything was so fast it was over before I realized what had happened ( no harm). The second time, when i was a couple of years more practised, I fell when going much slower. My instinct made me put my hand in front of me to stop the fall (instead of rolling). I then remembered, rolled and had a shoulder pain that lasted about a week (the strenght was transmitted there through the arm from the floor). I never had problems with my belt, but it showed me that this sort of things work better when you don't think about it.
just my 0.02 euros.