Touch wood my Powrtouch rollers are still sound after 3 seasons. If you are going far from home, take a sheet of the coarsest abrasive cloth you can get (try Screwfix) and a pack of rapidset Araldite plus some meths (to degrease things, not to drink) Then you can recoat the roller in the short term and keep going, while Powrtouch honor their warranty (as i'm sure they will) with new ones. I have a feeling some types of rough pot scourers would do the same job. Could be the subject for an engineering undergraduate project here.
After use on gravel etc, always worth a couple of minutes to clean off the roller surface before all the crud bakes on.