I wouldn't buy either of these and I certainly wouldn't be keen to buy PVC.. why have you settled on either of these?
Rinh a few rib toob repairers and ask what kind of warranty they will give on PVC or HYPALON repairs. It's usually longer on Hypalon
the two most established makers of Hypalon are ORCA and Fennel ( I Think) dunno if either of them do Hypatex
no Problem to retrofit anything to a GRP deck providing you have the space and the weight capacity
Searider, Tohatsu, Ribcraft Solent come to mind
Ribeye Hypatex vs. Avon hypalon