I drove the part today. If you want to drive slowly, the Rapperswil side is nice if you don't find the partly loose surface bad. I got on well with the racing bike, but it is slower.
I don't find the main street attractive either. Too many cars.
At the top of Lake Zurich, there seems to be a good path along the river course there. Looked good as an alternative route in the section.
If you want to descend and swim in between, you are in good hands on the paths by the lake.
I had no bath ambitions, but I wanted to have completely bypassed Lake Zurich.
Next time I will take the way over the dam to Rapperswil, between the upper and lower boats. It is much faster to drive and a lot more varied when changing perspectives, especially if you have collected a few meters of altitude beforehand. ;)