I don't have any experience with any outfitters but I will recommend some places for you to look. Units 4, 6, 7, 9, 10, 12, 16A, 17, 19, 20, 20A, 26 and 27 all allow you to kill 2 bears. There is a reason for that, the are a lot of bears in these units. Anywhere you go in Idaho will provide a better than average chance at killing a color phase. If it were me I would look at Units 6, 7, 9, 10, 12 and 17.
Go onto the IDFG website and click on the "Hunt Planner" icon at the bottom of the page, then click on "Find an Outfitter" on the right side of the page. This will take you to the Idaho Outfitters Liscensing Board Page. CLick on Hunting and then fill out the form by entering that you wan to hunt black bear, select the units you are intersted in hunting and a list of outfitters will be generated. Most will have a website, all have some contact info.