I finished the service and took it for another test ride. There was no noticeable whine. I did notice what I would call double back-lash noise when letting-off and throttling-on that I would call normal. As a result, shifts can be a little clunky.
The owner bought this trike used, the mileage/age of trike is not known. However, the mileage on the ODM is 57k. And the kit is on a 2005 GL1800.
Yes ... the gearbox in the rear also has a film of oil on it. Not to the point that I would worry about it, as in something leaking. Oil could be weeping from the "silicone gasket" between the 2 gear boxes, of from silicone oil over spray ... or possibly the gear boxes come shipped with a film of oil on them when new. The oil film does not appear to be coming from any seals, or axel boots leaking.