Hi - am fairly far behind, got an email notice though!
https://ratproofchickenfeeder.net/
Yes I have the higher lip part but haven't needed it. My standards - Buff Orpingtons and Buckeyes - can just reach inside the basic lip, and unless the front part is filled with crumbs/powder so the pellets are up at the brim they don't flick pellets out. Both Popcorn and Tedi are sweepers and I don't see stuff coming out unless the front is filled up.
Bigger chickens, or ducks, might be another story, can't they reach further and pull better? So depends on how they feed.
I did get the outdoor weather-proof styles and would recommend that. I still put a protector over or nest to the back corners because that is one weather-vulnerable part when the wind blows. Last summer I had a small piece of spare plastic roofing on top held down with three bricks on one that was out in the open (lashed to the lilac bush/maple sapling). For one in the covered run against the open north wire wall I fastened a wind block on that wall right behind it and that worked.
What I've got are two Medium ones, an old style 2019 one I got in 2020 (had the counterweight) and a new one (works by two springs on the door). I retro-fitted the older one with the springs, the guy sells all the wearable parts cheaply and I keep some on hand. The feeders aren't perfect or maintenance-free - the springs and pull bar will wear over time - but I'm happy enough with them, and am VERY happy with the support I've gotten since the guy is a small business and generous with his advice and help.
My one concern with the new one is that it has a lower back internal divider which goes lower, so there's a smaller space for feed to come through to the front, which should be good, but I'm not sure I've set it level right now, because I am pulling down feed from the back into the front a lot. It does come down into the main feeder area - but my gals can't reach that far back. I've got it secured with a rubber bungee which may be pulling it back, and it's set on pavers on litter, so things may have shifted.
HOWEVER, this feature/bug/maybe it's tipping backwards thing does make the chickens eat the crumbs that pile up in the front. I'm just spoiling them pulling pellets forward - "here, have some fresh pellets!"
Hmmm, I'm terrible with volume also except by a reference. I decant a feed bag once I open it, into clean large tall plastic pretzel jars, like this Utz pretzel container below, and I store them in a covered bin in our garage/barn, which is dark and tends to be cool even in the heat of summer. My idea is that the containers help hold in any smell better than an open bag so rodents aren't attracted. A 40lb bag of pellets will fill about 5-6 of these I think. DH is off pretzels now so these are hoarded items, they're very handy for all kinds of things! I have old glass & metal ones from my mother I store flour in.
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The Medium feeder will fit 3 of these? The Rat-Proof Feeder owner says the new Medium will hold 32 lbs of pellets. With four chickens last summer, two that were basically unwell, and with two feeders (anticipating the new chicks), consumption was slow between the two. So the garage was a better place for the pellets to be stored during summer heat. During this winter I was refilling by bringing one container out with me and dividing it between the two. At most I went back for another container and put that in them also. I just haven't lugged out more at once or lugged a bag out there!
I can test this volume question because I will be cleaning them out and refilling - right now I'm mixing the last of the Nutrena Feather Fixer with some new Purina Layena+ I'm trying and letting it go down as much as possible before filling with just Layena+. (I would stick with Nutrena, but TSC's available Nutrena Layer bags were much too old and the Purina was really fresh.)
