I used them on my 8. This was while Van's was still saying they don't do any good. Tracy Saylor told me they were good for 2 mph reduction in stall speed, and a 2 mph increase in cruise. I never flew with the other tips, so I don't know about that.
I think the version Van's sells is about half price if you count the lens kit for the lights. They are slightly different because they curve up on the ends.