I don't know whether you're still visiting the forum If you are the following may help you.
I bought a BOC Migmaster 130 Turbo a few months ago. It's a nice machine and I've been happy with it. Today I was reading some old Practical Classics magazines. I came across one from June 1989 which had a review of the "new" BOC M130 turbo. The machine is tested on mild steel with argoshield gas then on aluminium with pure argon gas and wire composed of 95% aluminiumand 5% magnesium.. The tester, an experienced welder, was impressed with the machine's ability to weld aluminium. The article refers to "dip transfer" and "spray transfer" arcs. The summary of the machine was that for its size it was incredibly good at welding alloy.