As a sideline to our contracting business we've been spraying primarily closed cell (2 Lb.) foam for 15 years. If you have air handling equipment in the attic spray the rafters so it's not working in extreme tempatures. I've heard the shingle warranty thing but never talked to a roofer that experienced it firsthand. Houses that are sprayed from the ground up are extremely tight and usually require some forced ventilation, something their hvac contractor should take into account. Sprayed an attic once, residents started complaining of headaches , turns out they had a defective furnace, been causing health problems for years. Did a little work for the government sealing mine and ventilation shafts, used it once to support a 2 ft thick concrete slab, 60 feet across, amazing stuff.
