Well, Ninja supports PATS, but I've never used it myself for "real" trading (i.e. lots of orders, modifications, cancels etc).
I would be very interested to hear people's RECENT experiences with PATS, with any of the larger FCMs (e.g. ManFinancial). Because I never really looked again at PATS after 4Q2002 (it was too unstable for my taste back then)