I just bought a damaged Lunar which has a GRP back end. I have found out that unlike a car due to the movement in a structure of a caravan if it has a knock its not just a matter of fill and spray. The GRP will keep cracking until you drill a hole in the end of the crack. Alluminium sides are just skinned over and are easier to repair on large or small knocks.
This is the only problem that I can see. Perhaps GRP becomes more brittle over time as well. I'm sure its cheaper to make from the start though.
Swiftman, I have an Abbey Vogue GTS, with one piece grp sidewalls and the main advantage is that there are no joins anywhere to allow posible water ingress.They look really good too, a very smooth finish.
The only possible downside that I can think of is if you get any damage, say a small area damaged, then its a case of either replacing the whole panel, at I would guess a horrendous cost, or being GRP, having it repaired, which shoud be relatively easy, and a lot cheaper.
Hi swiftman, Like you we have gone for Abbey with GRP walls, not sure if you have yours yet, we bought 2004 dealer special with fixed bed, which I seem to remember from past post you were looking for, Walls on ours look good, I am waiting to see if James replies to other posting about them not being repairable as I have not heard that anywhere else.We had small dents in last van with metal sides caused by bikes, awning poles, etc so we thought the GRP would stand up to the knocks better.
Awaiting delivery of a Vogue420 next month. Made the choice on the GRP being more resilient to scratching from hedges, branches etc dents and holes, as I have suffered all of these with an aluminium skin. The dealer also reckoned that there was a better insulation value as the GRP is thicker.
I have had my GTS nearly 3 years now, No dents scratches or knocks are showing not many people could get away with that on alloy sidewalls.I rate these GRP sides highly Pity about the rest of the Swift build quality! GS.