Many thanks for the MPC info, really helpful. I usually fly direct into BOS so haven't transited int'l to domestic at a US airport in a while. I suppose when booking that I momentarily forgot it wasn't just me traveling - I'm usually willing to give things a go if I think there's a reasonable chance of success. And no mobility issues; however, I can assure you we won't be setting any speed records transferring from one gate to another . (There are checked bags and it is UA to UA.)