This is my first review and only because the extension is so good. I was un-nerved by the fact it had no reviews but after a leap of faith, I will be upgrading all my Virtuemart sites to SEF Advance.
I have tried the 2 well known extensions and found they were just too complicated to manage on a daily basis. One was creating 000s of unnecessary redirects which Google punished by 50 ranks.
This does exactly what it says on the tin - it builds the URL dynamically so when a VM product name changes, so does the URL. A log is built up of 404s so you don't lose traffic. There is a control panel also that allows you to make adjustments and for me, this is perfect.
Installation wasn't a simple Admin upload but after an email to the developer, it was sorted very quickly.