According to DIR, sidemounts should be aluminium so that they have no effect (well very little at least) on bouyancy, but main backmounts should be steel.
When I say DIR rig, I mean I'll be getting at least a DIR compatible backplate, harness and wing. The harness I'll be making myself from 2inch webbing, then I'll probably get a DiveRite stainless steel backplate and probably the Rec wing so I can use it for singles and twinsets.
One part of the DIR idea I like is having the secondary reg on a short hose held by your neck, with the out of air buddy taking your primary reg. Apart from anything else, it means you're not carrying an octupus with a long hose along, plus you know the out of air diver is getting a working reg.
Should be ordering the webbing and backplate quite soon, but won't be getting the wing until I've got a job. But this thing will still cost me less than the Buddy Commando TD stab jacket that I was originally going to get, plus I can set it up exactly how I want it.
Was going to do some nitrox and then maybe trimix training, but providing I get onto this navy diver training, I'll be getting that training and being paid for it, so no point me spending the money on it now.
Matt