USAF CV-22, DOD photo
The Air Force Times is reporting the Air Force is considering using the V-22 Osprey for SAR, at least Combat SAR. They see these platforms as having an advantage where speed is critical. They also recognize that in other circumstances, agility may be more important, so they are not considering wholesale replacement of helicopters with these relatively large aircraft. The planned purchase of 112 HH-60W next-generation Black Hawk helicopters is still expected to go ahead.
It may be worth noting the Marines are already using their MV-22 for combat SAR.
In the not to distant future, we may have aircraft that combine the agility of the H-60 with the speed of the V-22.
Chuck Hill's CG Blog 
I am not shocked the USCG hasn’t looked into using the V-22 in a SAR role. I bet it would cover more area and more distance.
From what I have read, the extremely strong rotor downwash has kept the V-22 from being considered for SAR.
Not just the rotor downwash but because the entire engine rotates the “jet blast” exhaust from the gas turbines is fierce. The Navy is already having problems with flight deck damage.
Bell is working on a new tilt rotor design for the Army the v-280 I believe. The engines will remain stationary just the rotors will tilt. This will solve the jet blast problem and allow either engine to power both blades in the event one of the engines fails.