I usually flush, lately I have been using AN final finish. I make no claims that AN's crap actually does anything, but blind taste test done separately with my friends and family have always picked the joint that has been flushed. I roll 2 joints, one that I flush the plant and 1 that I didn't flush. They smoke half of one joint and half the other and do a blind pick of their favorite.
When I run the tests I make sure both plants are cut, dried, and cured at the same time. I haven't tested a flush with AN's final finish vs just plain water to see if anyone can tell the difference. It was just cheap at the time and I said wtf and bought it.
Best to just test it out yourself. If you and your friends cant tell the difference , then why bother. The day that my friends fail the test is the day I stop flushing.