RE: gravity or timed feeders
If you're trying to get as much protein into your herd as you can.....go with gravity. I know a guy here who got 350lbs eaten in 4 days!
I use a 200# timed feeder on the property I hunt. I do so: 1) because I "think" I'm helping out (whether I am or not.....I feed about 100#'s a week) & 2) to hold the deer on the small parcel (or at least give them a reason to pause) I hunt.
The deer I hunt are gonna be around......I just think it's not hurting anything....and I dont hunt over the feeder. I also have a food plot (2.5 acres) about 300 yds away.....and I won't hunt within 400 yds of it.
I time my feeder to go off 1 hour after sunrise......and about 2 hours before sunset. if they wanna free meal around my parts....they're gonna have to risk dining during shooting light. Too much competition for foodto become nocturnal.
Good luck with whichever method you choose.