My only experience comes from two .177 PP700 pistols (W and SA), and one .22 PP700W. All super accurate, variable fpe due to poor set up and reg quality. The latest one, the transfer port was very nearly not drilled through.

Great care needed to explore ALL fill pressures to ensure it’s legal throughout the range and set it to that part.

Plusses? Cheap, accurate (JSB exact 4.52), reliable and a fiddlers paradise!!