You are going to get mixed advice because every part of the country is different. Where we are, you can see all the newbies with their new rigs in the storage lots with covers in the fall, and by spring the UV and wind completely destroys the cheap ones, and the expensive ones may still be there but get ripped from roof equipment, etc. Down south, I think they are probably a must to keep vegetation off the rig.
Bottom line, just see what other folks around you do, not what people do across the country. Your metal building will ultimately be the best, that is what we have done for the last 11 years.
