On my dad's railroad, we used aluminum because in 1980, it was the only way to get curves wider than what LGB produced. At the time, we used it for track power with no difficulties over the 4+ years we ran power through the rails. When we switched to battery power, we just stopped cleaning the rails. Expansions followed using more aluminum rail because it proved quite adequate and inexpensive.
Once I got through school and finally bought my own place, I opted for aluminum code 250 rail because I liked the smaller profile, it was cheap, and based on my experiences with my dad's line, I knew it would hold up well when built on a good foundation. The only thing I didn't like about the aluminum was having to paint the rails to get them to look realistic. I tried pre-painting them, but the tie strips I was using were so tight that they'd strip the paint off the base of the rail as I slid them on. When I moved, the track stayed with the house, so I didn't have the luxury of taking it with me.
Now, I'm using the AMS brass code 250 track. Really, the only two reasons I'm using that instead of the aluminum is that it was actually comparable in price (don't know if that's still the case) and I decided that I liked the way brass weathered, so I wouldn't have to worry about painting the rails out here. The fly in that ointment is that the particular alloy AMS uses is very slow to oxidize, so it's still--three years later--a bit yellowish.
Later,
K