ok, did not see any thing first troul around will look again. Boss is looking into replacing some outdate equipment around campus and ask me my imput, 410A was the only replacement I could think of right off hand. Was interrested if there was any new refrigerant that may be a long term replacement. Lot of the guys I work with do not like the high pressures of 410A.
If the equipment is still good.... there are replacement (NOT drop in, NEVER mix R-22 with something else). Most require recover, N2 flush, new LL drier, replace schraders, then charge with new. Some play acceptably with MO, some need POE. Most operate similar to 22, yet at 85-95% capacity.
There are lots of threads on this recently, I think I have posted at around 5 or 6.
Personally... Install 410 equipment. Solves lots of problems and is a better value for the customer. Higher pressures are not a big deal... just follow proper safety procedures we should be doing on 22...