My experience has been that Polycom are reasonably hassle free and work well. Telepresence is a lovely system but I've never managed to justify the costs involved, you can say it cuts down inter-office travel but to be honest I've never found that to be true, exec's and managers (me included) still like a jaunt out of the main office so it just replaces phone calls with video calls for the most part and it's a big cost to do that...