Its most important how the unit is built, particularly the roof. I have a Dutchman that's just as pretty as a picture, but the aluminum roof was a bit bulgy. Turns out the company engineered some nifty trusses using 2x2 joists, and 1X2 flat for the curvede arch, with little pieces inbetween, and some neat little steel bits tro hold it all together.
That's all fine, but on top of the trusses on 16" centers, they put an insulation board (3/16" cardboard), and the aluminum skin - loose fiberglas bats provide no insulation, no capor barrier, now the roof is cracked from flexing, and the cardboard is soggy.
Moral: know what's under the roof.
As far as the rubber is concerned - many of the new units are vinyl - but either is as good as aluminum in my view - and a lot easier to repair when, not if, it needs it.
Just my 2cents
PWR
That's all fine, but on top of the trusses on 16" centers, they put an insulation board (3/16" cardboard), and the aluminum skin - loose fiberglas bats provide no insulation, no capor barrier, now the roof is cracked from flexing, and the cardboard is soggy.
Moral: know what's under the roof.
As far as the rubber is concerned - many of the new units are vinyl - but either is as good as aluminum in my view - and a lot easier to repair when, not if, it needs it.
Just my 2cents
PWR