[Tom '74 911]

Jeremy -

Take another look ay iRacing. The track selection is pretty darn good and while there are no Porsches, there are some good GT car options w/the Corvette GT1, Australian V8 Supercar, Mustang GT, Mazda MX-5 etc... plus a Daytona Prototype and some open wheel cars. I've only dabbled in rFactor so I can't really compare the two, but iRacing is about a realistic a driving sim as I have seen in terms of track accuracy, car response and general feel. I bet they have a trial vis which you could check it out.

Tom