I have a powertwin and I love it! (Cannot commet on P&T as I have not actualy used one, but did not like the rear seat position).
Jane is really very light to push and steer, even when fully loaded with kids and shopping. You have to lock the swivel wheel when going over really stony ground(especially uphill) but I do use mine on footpaths in the Lakes. Locking wheel is a half turn of a little button on the front. Dead simple.
I also bought the carseat to go with it for the baby, but very rarely use it as the rear seat of the pushchair drops to almost horizontal, which I prefer for my LO.