Easy there
The cheaper Old Towns have seats that are even worse than the seats of aluminum canoes, because not only are they hard, but they have front and back sides that prevent you from tucking your feet under them. Their cheap canoes have the very worst seats in the canoe world, in my opinion.
You are greatly over-stating the tendency of aluminum canoes to become dented. I'm not sure about the brand that the original poster is getting, but Grumman canoes are mighty tough, especially the shoe-keel model. Most of the really old Grummans I've seen have been quite abused, but the dents are few, and MUCH less significant than the warpage that occurs with Ram-X plastic. Alumicraft canoes weigh much less than Grummans, but even those boats usually only have minor dents when abused. The "normal" dents you get in Ram-X plastic cover a distance of two to three feet and are four to eight inches deep. Ram-X plastic won't maintain its shape at all. It's hard to over-state how bad that material is for boat building.
As far as reflecting light goes, don't forget that the poster is buying an old boat. OLD aluminum is dull gray, and doesn't reflect badly at all.
There's nothing wrong with that "crap foam floatation" either. It works as well or better than the floatation provided by low-density Ram-X plastic. The only downside I've seen with foam floatation is that you need to be careful that carpenter ants don't make a nest there while the boat is in storage.
I think the original poster has the right idea. Of the two cheap boats available to him right now, he's picking the one that will handle better and paddle more easily. He says he'll be willing to spend more on a different boat in the future if he "catches the bug". If that day comes, used aluminum canoes can be sold for the price you paid for them, which can't be said for Ram-X, which just gets uglier and more warped the older it gets.