I also did the low temp method... Seasoned with garlic, kosher salt, black pepper. I seared the rib first. Then I set the temp around 225 on a boned rib. I put a diffuser in the grill with a shallow disposable pan to catch the drippings. Cooked until the internal hit 125 degrees and let it sit for 45 minutes... It was pink right up to the edge. The advantage of cooking low and slow is that the meat does not shrink as much, losing about 8-10% in weight... Cooking at 325 loses about 15%, a big difference.
The only problem I have now is that I am almost out of lump coal. They only have lump coal in spring in Hawaii and the stores run out after October. I bought four bags of Royal Oak after Halloween and they are almost gone. The stores ae sold out so I might have to revert to briquets which leave a big mess afterwards. There is local lump coal available made from kiawe (a local mesquite) but it sparks a lot and has a strong smoked after taste.