I have the RWD conversion done on my 2008 and it's a huge difference. These cars were designed way back in the early 2000's and many complain that it feels like an old part time 4wd pickup at slow speeds, grabby, etc, clunky. I've sold this to many customers and they've never gone back to awd after. I can 100% say just doing this mod alone, makes this faster than a Superlegerra. At least 04-08 non SL vs a 2008 SL with AWD. You will pull on an SL every time. I have a video on this I will dig up to show.
Going to RWD drops about 125lbs off the car including unsprung and rotational mass; makes the car significantly faster by reducing the drivetrain power loss between the engine and tires; increases clutch life; increases fuel economy; makes the car easier to drive at low speeds and makes clutch engagement easier. 100% reversible with no permanent modification to the car and is compatible on both manual, E-Gear cars. I have 2-3 sets left currently if anyone needs contact me.