I'm replacing a 18yr old Bryant with a Rheem. For my budget, I'm looking at a 14 SEER and using R22 instead of 410. From what I've read, the only difference between 22 and 410 is the potential R22 may someday be hard to get. But, from what I read this will be 15 - 20 years from now, will never be totally phased out in the life of this unit and there will probably be other alternatives. Correct, of is it a mistake to go with R22? Thanks!!!