I have a 1974 911 that I'm working on and have entirely redone the engine and suspension on. Much like a RIB, they are fast, no frills type vehicles. It has the same motor as the car you're interested in and a lot of the same upgrades. It is fast (my lightened car can hit 160 mph), fun, and with the Triad muffler on the 2.7, it should sound sweet.
As to whether or not you should sell your RIB and buy this car, I can't tell you there, but you should know that owning a 911 is not a cheap proposition, by any stretch of the imagination. I think that car is a decent deal (with the exception of the oil leak and the sunroof issue, which could both be big problems in their own right). If you blow the motor, I doubt you'll be in the shop for any less than 10K if you want it rebuilt right.
Right now I have a 2.7 race motor in my car, but if I had loads of cash in the bank, I'd replace it with a Euro-spec 3.2 and be done with it.
If you have Porsche questions, let me know. I did some side work as a P-car mechanic, race crew, and have been working on my car for a long time.