I have Thule upright carriers for my bikes and have never had a problem whatsoever with them. Yes there is some sway but it's not like the bikes are coming off the roof. It certainly does no harm to the bike to have it sway and to be perfectly honest with you I would rather have the bike sway little than have all that pressure being taken up by my front fork. I have also read that the fork mounts do cause pressure on the forks and can cause alignment problems.

As for taking up room on the roof, I don't think it makes much difference which system you go with . The bikes are the same width with or without the front wheel on and you can't put anything in front or behind them once they are oneanyway. I can easily fit 4 bikes on my rook at one time with the uprights. The other problem with fork mounts is where to put that front wheel when it's not on your roof. I hate to throw it in the back of the car where someone might throw a heavy bag or tool box on it and end up wrecking a few hundered dollars worth of wheelset.