I've been using a HHA for 7 seasons and I hunt spot and stalk or calling 98% of the time. I set mine at 30 yards and know to hold a little low (2 inches) at 20 and a little high (4 inches) at 40. Anything past 40 I take the time to adjust the sight. Shot my 2010 bull thru the center of the heart at 55 yards after ranging him and setting the sight. Shot my 2011 bull thru both lungs at 30 without having to move anything.
Of the 20 or so elk I have killed with my bow the average shot "out west" has been 27 yards so the system works well for me! I prefer the uncluttered sight view and so far the sight has been tough as nails. Never had a problem with it.
The biggest drawback in my opinion is that is your adjust anything on your bow re-sighting in is more complicated than just moving pins at each yardage. There are some cool computer programs that would make it a lot easier but I have yet to go that route....probably will soon!
I'm with Joe! I love my single pin slider, and use it the same way he does!