I like Aluminium. You can interpret peoples' comments here whatever way you want. WHat is "warmer" to some sounds "dull and flat" to others. What is "bright and articulate" to me may sound "harsh and brittle" to others.
As a slap player, you can get some beautiful treble out of aluminium cones (well I could). It's all personal preference.
(As a side note, I tried the 450 W Behringer 'ultrabass' head through their 1000 W 8x10", aluminium cones. The cab was ok, better than I expected, and the head was probably a little better-sounding than expected too (except the 'ultrabass' feature - what a gimmicky waste of time). But what surprised me most was the lack of volume. My 350 W Trace through one 2x10" was louder than this whole rig cranked to full!!! I'm not sure if it was the head or the cab, but from a rig that size I expected to be rocked, and I wasn't)