Aluminium has its problems, but it has been my favorite boat hull material. It is light, can take the knocks, and is relatively easy to repair. We've had a 21 foot aluminium jet boat for maybe 15 years and it has been permanently moored in the ocean. We've also had aluminium dinghys.
The bigger boat needs regular replacement of the bolt-on zinc anodes to avoid corrosion damage, and we have to use a special expensive antifouling paint to suit the alloy. There is some corrosion on the boat, and we did have to have a patch welded in for one peculiar bit of serious corrosion that occurred. But overall it is just fine, and it has plenty of life left in it.
Our aluminium dinghys haven't fared quite so well, but they virtually never get washed with fresh water, and they are real workhorses. One was a riveted boat and it sprung a few minor leaks. The other is welded, and it has cracked in one or two places (not at the welds). They are very light which makes them easy to carry and hoist on to the big boat, but they can blow away in the wind so you have to be careful.
Aluminium is good and will last well, especially if you take care of it.
I recommend that you flush your outboard and do regular maintenance including changing the angle drive gearbox oil. However I know of folks that don't do much maintenance on their outboard, and they generally don't flush them.... and they seem to get away with it. I was told once that damage from not flushing may take ten years to take effect.
Here's the aluminium utility. My brother and his family have a home on an island that you have to get to by boat. Here he is with one of his motorbikes... he has no trouble at all in getting them on and off the bike on a six-inch plank.
