John,
I have a mix of Aristo, LGB, & USA 332 brass track, with one LGB NS switch, and about 50 ft of Micro Engineering aluminum track. I used to have 100 ft of the aluminum track down, but replaced 50ft of it with brass on a line that would occasionally be used with track power. There was a noticable difference in conductivity between the aluminum and brass. For battery power, the aluminum track is just fine.
JimC.