I'm a big fan of Mobil 1 synthetic ATF as well. It seems to have better cold weather behavior, i.e. the tranny is much smoother when starting out when the temperatures are below freezing. I also use it in my power steering fluid reservoir.

Considering that is only costs a bit than the non-synthetic, and you only change it every couple of years (depending on how much you drive) the improvement is well worth it.

Chris Blanchard
1984 300SD 145k