G wrote:
SNIP

Since it doesn't seem to drip/leak when I use my
plumbing fixtures, I'm going to assume that the leak
starts somewhere ABOVE all the joint areas and hopefully
a nice long-term remedy will be that 180 deg "Return
Bend" as you suggest. I guess the worst thing is that
I'll have a tiny bit of air escaping from the vent pipe
into the house, but I assume it won't be enough to cause
problems with smells & things like that.....

Sound about right on all this?

Yep~!