Thank you, Jonas, for your detailed and objective comments.
I am happy with the RJ adapter and I probably will be happier with the other adapter. But, you yourself have to decide how to use the lens and how much you are willing to spend on the adapter. Plus, there are a lot other options out there beside the Contax G lenses.
One thing I did find out that for me, with the RJ adapter, if I place my left hand on top of the lens and use my thumb (pointing down) to turn the little focusing wheel, it works a lot better for ME. It was a bit odd at the beginning as most of us hold our lenses with our hands supporting the lens from the bottom, and focus at the same time. I hope I make myself clear without taking a picture .