assume the High 5 is stainless? I've been told to stick with aluminum as it's better to break/bend one instead of having your outdrive get pulled off.
Yes it is stainless. but due to it having a big plastic slipping hub on the inside ther'e little chance of your drive recieving any damage. the plastic is the weakest link so in practice breaks first. but really... you are gonna ahve to hit something pretty hard and pretty badly to do any damage. The torq flo internal hub comes with the prop and can be replaced for about 25 bucks.
Stainless will always outperform ally as it allows a thinner blade surface, thus more grip and less drag. the high 5 is pretty much the creme de la creme for a boat like the 1800... it makes the world of difference. but comes at a price.. about 480 dollars :shock:
However, it will outlast an ally many times over so i'd argue it worth it for that, let alone the awesome performance boost 8)