Roll up doors aren't perfect but I'll take a roll up any day over a slider.

They're more likely to freeze up but much, much easier to bust loose.

Rollers wear out on any door.  Different design but they all wear out.  I put around 400K miles on my Wilson GN and I replaced the door once. 

Tracks are lined and liners are relatively easy to replace

I bought my current trailer off-the-lot so I couldn't choose a roll-up.  I miss it every day.

Biggest negative is the noise.  They bounce and bang.  Impossible to drive slow enough on rough ground to avoid it.

After 400K miles my tracks were still perfectly lined up.  I had to replace hinge bushings on the door I think and probably cam locks, but the tracks were never touched other than re-lining.