I have a sl600, and there have been a very few times when I would like to turn off the ASR mode. However, there have been many many more when it has doen a masterful job of keeping the car on line when traction changed abrubtly.
Di it with caution. There are a couple of kits out there, and it HAS to be done right. All the computers and sensors work together and you can easliy screw lots of things up.