All the Pro Targets I have owned had free floated barrels - not had a problem with any of them.
Not owned one with the clamp in place - so cannot comment on how it would shoot. It may make no difference at all. If you are having problems with your PTs accuracy then It is worth trying to narrow the problem down.
I do know that I have only seen one with the barrel band in place in the last 10 years. Even Air Arms removed it on the Mk3.