Have we established a general consensus about retrofitting with MO99? The reason I ask is because Im being "persuaded" to begin using it whenever possible by the owners of the apartment complexes where I work...and by "whenever possible", I mean anytime that they think it will save them a dollar. For example, I found several air handlers that had been replaced recently, but whoever installed them simply connected the electrical and ductwork and called it a day. They werent pumped down (they didnt even close the valves) and they just left the linesets dangling in the attic. And theyre wanting me to tie the lines in and use MO99 in them, simply because its cheaper. Id prefer using R22 for several reasons, not the least of which is that Ive always been very skeptical of drop-in replacements, so I thought Id try to learn the pros and cons of it here from yalls experiences with it. Ive researched it somewhat and am still on the fence about using it. The equipment Im dealing with is mostly 1.5-2.5 ton split systems which seem to have been very poorly maintained before I started working there, many patched together mis-matched and barely running, and others not working at all. Needless to say, I have my hands full, but I always welcome a challenge. Thanks in advance for any suggestions/advice.