Currently I experienced an industrial refrigeraration installation running on R-417A. As I was told this refrigerant is used as a drop in for R-22. However the end-user wasn't happy at all since he had to pay for 3 compressor overhauls over 1 year.
As independent advisor I was asked to analyse this problem. So far I took the job but until now no results. Who can help me with this problem or is willing to share his experiences with this refrigerant. Some specifications;

System; two stages with liquid subcooler
T low; - 50 Celsius
T intermediate; -10 Celsius
T high; + 35 Celsius
Oil; Suniso 4 GS (mineral)