I bought the Losmandy OPWB for my older G11 that had about 12 or 13 arcsecs of PE prior to the upgrade.
Due to the age of my mount I also had to upgrade the gearboxes. I originally bought 2 of the McLennan gearboxes which have had great reviews, and having seen them they are much better quality than the Losmandy ones. However, the McLennan gearboxes have a metric shaft and the Losmandy motors have an imperial diameter shaft, so the supplied Ruland coupling would not work, and it proved too hard at the time to source something that would fit, so I bought some of the standard Losmandy ones and fitted those instead.
My PE was reduced to 3.56 arcsecs peak to peak (
see this thread), which just blew me away. Definitely a worthwhile upgrade in my opinion. I would still like to fit the McLennan gearboxes one day though nd see what difference it makes. But then again 3.56 arcsecs is good enough for me at the moment.
I will see if I can track down the PEMPro graphs before and after, and post them.
Adam