After a lot of research, and visiting with Cape Horn & Scanmar (the Monitor Windvane) at the Strictly sail Pacific in Oakland (April 2012)... I have selected the Cape Horn Windvane!  Its clean install, available (and functional) off-center stern mount, no lines in the cockpit, proven durability, etc etc... SOLD ME!

I'm very happy and surprised, because I did NOT want to put a hole in my transom! But after reviewing all aspects... the Cape Horn makes total sense for me.  And, Eric Siotte (nephew of founder) does "one-off" installs... And,ordering it during the winter off-season saves me $$$, and it is still less expensive than the Monitor, with the professional install!