Thanks Nick. Perhaps you're right about PTgui. Nevertheless I prefer having the manual control I get with the NN5 upper rotator.
Paid another visit to your NN5 accessories page and found the RP1-38 rail plate. I see in the last two thumbnail images on that page that it's shown attached to a RRS lever clamp with a 3/8" threaded hole but it's hard to tell how the plate & clamp are being held together. Is there a 1/4" screw passing through the RRS clamp and being torqued down against the threads inside the brass insert, or is the brass insert holding them together by screwing into the RRS clamp's threads? The latter doesn't seem likely, but the insert appears longer than the plate is thick where they're pictured together, that's the reason I asked.
I also noticed the other low profile plate comes with a shorter camera mounting knob. Would that not be necessary for the RP1-38 as well?