Gary Pfisterer will lead the Dhaulagiri Circuit trek for The Mountain Company, I have copied below some information about Gary's background and experience:
Gary is known as one of the great leaders in the mountaineering world (per EverestNews.com). He has led many expeditions, often with his late wife Ginette Harrison, including to K2, Kanchenjunga (three times!), Shishapangma, Makalu, Dhaulaghiri and Lhotse. All of these expeditions, with the exception of Everest, were achieved without the use of High Altitude Porters or supplementary oxygen.
Gary has summitted Everest, Cho Oyu, Ama Dablam, Kilimanjaro via the Heim glacier, Mt Logan (third unsupported alpine style traverse of East Ridge) among many others. He has led treks throughout the Himalayas and Karakoram including the epic Lunana Snowman and Snowlake Biafo- Hispar traverse.
For more information I suggest you take a look at The Mountain Company webpage for the Dhaulagiri Circuit trek. It would also be worth reading the Blog entry with Trip Report for Dhaulagiri Circuit May '08