As world class as Rahal and Feller are, and I'm intending on going to Rahal myself, I wouldnt go to either for FUE.
I think there are better clinics out there when it comes to FUE and the good news is that they're typically cheaper and closer.... in my opinion Europe has the edge and I would consider Bisanga, Feriduni in Belgium, Lorenzo in Spain and a number of clinics in Turkey dare I say it.