Prodrive 550s are very thing on the ground. I've seen most other cars of the GTS GT1 class in private hands out and about at track days etc but not them. Nor do they appear for sale.
According to DSC there's about a dozen that exist. I assume the Le Mans winning car is still at Prodrive but haven't seen any others in public eye.
Even the 575s, the Italtechnica and Weith 550s can be seen at hill climbs but the Prodrive cars seem to be locked away.