Steve, all my divin has been on single 15 and pony so far. 3 years after starting my divin i'm just about to strap on my twin 12's because i want to be doin slightly deeper for longer dives. All the YD gigs i've been on there has always been a variety of kit configurations and levels of experience. I've always been included and looked after very well by DM's on a single, DIR boys all in black or the rebreather crowd with their boxes of death.
Best advice i could give you is just be straight about your level of experience before you get on a gig and you WILL be looked after and definately not be made to feel out of place.
Call me fat again an i'll kick yer face in
