Aluminum hulled RHIB's have a good reputation. I'd have preferred one to the fiberglass hull that I settled on, only because it was less expensive. Now, if you want to talk about cruising hulls (sail or power) it's a wholly different matter. Electrolysis seems to be the main bugaboo of aluminum hulled boats. Don't ask me why.
Here's a discussion forum on that topic and there seem to be as many opinions as contributors.
Different grades and aluminum alloys probably factor in how the hull stands up to electrolysis....and you dare not use the wrong kind of antifouling bottom paint.