I've never compared the actual performance of the two lines, but I really don't want to reward companies like all-clad for the 5-ply and 7-ply marketing nonsense.
It's not too hard to imagine that the 5-ply pans could perform reasonably well. If the steel layers are thin enough, these pans would act a bit more like disk-bottom pans with thicker aluminum. Which is to say they'd be better at some things, worse at others.
What I like about the AC triply is that they're thin and fast, so I'm not really looking for changes here.