In my experience I'd personally prefer a CPR on a system than an MOP valve, but the systems we install rarely see either and are more often than not rack systems. An MOP shuts on pressure - where its quite possible the comp would not be pulling max amps in that case, at least with the cpr you know you are limiting system performance ONLY when its required. Although granted CPR's freak a few people out - I've seen CPR's used in strange situations... like to limit HP on startup after defrost... try to figure that one out - its called making up for poor engineering!!!

The manufacturers concerned (Buffalo and Heatcraft) do thorough R&D testing - they don't print these things for the fun of it (got a good laugh out of that post!) its just that like anything thats been lab tested - its never exactly the same in the multitude of applications and engineering variables that can go into a sytem. Sometimes you need to find what works for you.... if its pumping down the evap then so be it - just don't whinge to the mfg if you get coils icing over time at their specified defrost duration.

I'd be interested to know who that engineer at actrol is that says bitzer say its sweet to omit cpr's on their LT comps - this comes down to system design - maybe bitzer know the said engineer and are confident he sizes sytems generously, however there are guys out there pushing the limits and still engineering for lower ambients to save costs and win jobs, even an MOP won't save these systems - they take forever to pulldown after defrost for the obvious reasons, thats why that engineer shouldn't be making a blanket statement like that, if it was correct bitzer would publish the info which I bet my bottom dollar they don't.