Glyn, the only thing I'd say is that we do have commerical partners who pay to have a presence on OUTDOORSmagic and without that and similar commercial deals, there wouldn't be a site. That said, in cases like this, I don't think there's any problem with you responding to a thread like this, it's all just a question of common sense really.
I've used the Primus Himalaya Multifuel btw and my take is that for expedition use, I'd still prefer an MSR XGK - the needle jet makes it easier to clean and it's massively well proven. I wasn't that impressed with the Primus's burner performance using gas so if I thought I might be in a position to burn the stuff, I'd chuck in an ultralight stove like the Pocket Rocket as a stand-by option.
I'm not saying that the Primus isn't a good stove btw - it's good kit - just not my personal preferred option for serious use. XGKs burn diesel too - nasty, filthy, smelly process necessitating lots of cleaning afterwards, my advice is to give Derv a miss if at all possible.
