I haven't seen Protoshare, but I've just looked at the video and I'm definitely going to give it a look, and I'll write up what I think about it here. It looks very promising. I have to say, I have a natural reluctance to go for monthly subscription models. In my line of work wire-framing is only one aspect, and there might be a hiatus of several months and then suddenly I'll be working with a team at a clients. So subscription is not ideal. Still it's clearly something I should have a play with. Thanks