No ill effects so far but let's see what happens with 3' of heavy wet snow on the roof this winter
When I was restoring my Starcraft with aluminum roof, I discovered it was not built well enough to walk on without some type of added support. I used pieces of plywood and extruded foam to walk and kneel on.
The first few years, I got on a ladder and removed snow with a roof rake. Last year, I did nothing. The roof is still OK but if we get a wet snowfall or the snow builds up to around a foot or so, I'll break out the roof rake and remove the snow. It only takes less than an hour to do a fairly good job.
FWIW, I added two small wheels onto my roof rake blade. This allows me to push and pull snow off the surface without worrying about the blade doing any damage.