Given that you are 6" all the way, using 2-3 feet of flex hose will be
virtually unnoticeable. I did a test set up using 6" metal flex hose
vs. 4" PVC. From an anecdotal point of view, we are talking about the
difference between hurricane force suction and a nice breeze. Go for
what is easiest to do. You've already done the big improvement by
selecting 6". Just be sure to protect small animals from getting
sucked in!

Bob