I realize that I'm about 6 months late to this thread but I stumbled upon it while researching aluminum RIBs. In talking with Nick Jackson this morning about his 500# davit vs his 1000#, there's about a $1000.00 difference in price. I have since discovered that I can buy a Highfield 11' aluminum RIB and motor and be much lighter than a comparable FRP & motor. Less weight, smaller motor, planes faster, more economical. Bonus? I'm buying a Nick Jackson #500 and saving $1000.00!
500# Transom Model
Walt, you head it here first. I prefer FRP to Al. The reason is weight. Of course you could ballast up your Al to the weight of FRP to accomplish most of the benefit of a heavier dinghy, but it wouldn't be quite the same, as the rest of the design is dictated by the lighter weight, including the choice of power.
Try both out if you can, in rough conditions. I think you will find the improvement in the ride in heavy weather justifies the extra weight, bigger outboard, more robust davit system and the associated extra cost.
In sunny and calm, I prefer the lighter weight too.