I'm a motorhome guy and know nothing of 5ers
except that I like 'em
But I have had some experience with Filon.
We had thousands and thousands of our dollars
invested in a Fleetwood Class A, whose outer
skin was a Filon material. The sidewalls were
"Vacu-bond" construction (a glued sandwich)
and it delaminated on us (the wall came apart).
Fleetwood said they'd replace the whole sidewall
for $5500 at Riverside, Ca., but we'd have to get it there and pick up all motel expenses, food, and etc...while they fixed the coach...
too much, as the MH was only worth 16K at the time of delam..we traded it off for a Newmar with gel-coat sidewalls, like a dragboat hull.
Nothing to delaminate.