I think the gt3's are great cars. This has the solid and proven Mezger motor with water cooled heads. I have heard that the vehicles do have RMS leaks when not used. I believe the RMS seal is a low drag deal which uses crankase vacuum in some way to complete the RMS seal. So buy one and drive the crap out of it
Btw the 996 gt3 may not be as pretty as the 997 but they are lighter, more raw, and have a whole lot less electronic complexity. Since your coming from an SC I bet you will appreciate all of these points.