I don't know, I used to believe the only way to do beer brats was to grill them then put them in the beer bath. But, I watched Bobby Flay (SP?) one day and decided to try his way. Put beer and other ingredients (Garlic, Onions, etc. I perfer a dark Ale) you like in pot. Put pot on grill, make small cuts in brats (I know, never cut the meat, you lose the juices). Place brats in said pot and heat (DONT BOIL) until brats float. Then, pull brats and grill till nicely browned. These are the best brats I've ever had and I lived in Germany for 6 years and ate a lot of brats! The beer flavor really gets in the brat. If you grill them first, that "seals" them up and the beer (and other ingredients) can not get in.
This is my new way to cook brats, and I truely believe, if someone trys this and is honest, they will perfer them too.