@maxxjod: Thanks for the links, I'll contact them
@mr.ed: Pretty much all aluminium chassis' on 1/10 buggies are 2.5mm - some are even 2.0mm (like on the Schumacher K1), and the same counts for carbon. The only car known to me to buckle alu chassis' is the Centro (C4.1) - not surprisingly when you don't have sidepods or another type of bracing to restrict longitudinal flex.
I'm well aware Aluminium doesn't work for all parts on the car - such as suspension arms and shock towers - but for this job I think the specific alloy+hardening combinations are an excellent choice: It is way stronger than Carbon Fibre or GF (this refers to strength, not it's ability to flex), it puts weight low down in and close to the centerline of the car - the weight helps calm the car down, the position of the weight is helpful for the CoG and prevents the necessity of stuffing adhesive weights all over your car.