crackerdog; no, I don't have one yet, and I don't know anyone who has one that I can play around with. Even my local bike shops don't keep them in stock.
nubcake, i'm not planning on using freeloader bags (at least not initially, this set-up is going to be all about hauling two kids, one of whom needs a copilot-type seat). So (I think) my only concern is how much the v-racks can be squeezed together ... i.e., if there's sufficient flex in them. Are you saying that you think that there is?