Another thing to consider is the technicality of the rivers you most often frequent. If you know you will be making contact with alot of rocks, sticky rocks, lean toward glass. If you are constantly fishing in water that is not technical it doesn't matter as much. I have found that Aluminum tends to track better, which is important if you plan on pulling plugs alot. Heavy water can really boss a glass boat around. If you need to perform alot of technical manouevers glass is easier to control.

But I am sure it depends on who you ask...

I have aluminum...

Rowed several glass boats and just can't seem to hold their line as well, spend too much energy trying to stay straight vs. hold your river position...

...and the wind will ruin your whole day in a glass boat...

Hope this helps a little....