I had VGs installed on my Sedan after a few years of ownership. I felt that it was worthwhile. At first, I did not feel that it made much of a difference, but the more I flew it, the more I liked it. At normal cruise it does not make a difference, but when slowed up the controls felt more solid. It was hard to make a bad landing, especially on floats.
Power off stalls were coming in at around 45 mph indicated, resulting in a clean break. That's not noticeably different than before the VG installation, but my ASI was way off anyways. At cruise I was indicating 115 MPH, which was pretty optimistic.
The difference in control feel was the biggest thing. Of course, the Sedan is hard to get upset anyways.
Another nice thing about the VGs is that the weight is negligible. As with any flying contraption, the more that you can weigh less, the better your performance will be.
Take care!
By chance, were you at ENA late Thursday afternoon? There was a nice two-tone Sedan around in the air in that area.