What do people say?
When we tell the people we know about our zoning, they look at us with sympathy, the way you would when learning about a death in the family. We actually have 2 acquaintances who are teachers in the district - 1 of whom is at this school. They both told us to avoid the school while staring us in the eyes. These testimonials have essentially sold my spouse on moving, but in my experience teachers have always complained about students and their parents.
That's not be my experience at all. If multiple teachers think their school is crap and they tell you that, you can pretty much hang your hat on it.
My experience is that parents who kept their kids out of the district will warn you away even if they have no insider info because they want to believe that they made the right decision. But if parents and teachers in the district and at the school are telling you to stay away, that's pretty damning.
This. We had a similar but less striking choice, with two middle schools -- one classic UMC and loved by all, the other one town over and a step down the socio-economic ladder and disparaged (in hushed tones, of course) by the folks zoned for the other. We, of course, are zoned for the "lesser" one. But one of our neighbors teaches there and gets visible angry when people pull all sorts of strings to try to avoid sending their kids there -- and the Principal is really enthusiastic and supportive of the kids and all sorts of other good things. So we sent DS there, figuring we could always try the more expensive options if the "free" one didn't work. And he loves it -- on the academic side, they have plenty of honors classes and good teachers (several of whom went there themselves as kids and specifically came back to teach there); and on the social side, he is making friends with a whole bunch of different types of kids, which as a public school brat myself I see as valuable in and of itself.
But teachers warning you away? Oh, hell no. There is a difference between "good enough" and "actively bad." Yes, you are the most important influence on your kid,* but you are not the only influence; poor teachers, disruptive students, kids who don't care about schoolwork or who are so overwhelmed with their personal situation that they can't focus on it -- those are the kinds of things that can create a bad learning environment and lead your kid into a bad attitude about school that all of your lectures and lessons can't overcome.
If you seriously want to consider staying, then do some legwork. Go talk to the principal and teachers, see how they talk about their coursework and the school environment -- are they energized? Do they have plans to improve things, and do those plans make sense to you or just seem like shuffling the deck chairs on the Titanic? Are there any physical safety concerns/discipline issues? What opportunities do they provide for the kids who are more advanced? Do they have things like music and art, or have those been stripped because of budget concerns? And what about middle school and high school -- what are the AP and honors options at those schools, and will your kid be provided the classes and background she needs to be eligible for those classes later on? (As just one example, our MS starts algebra in 7th grade for the advanced kids, and that path gives them the chance to get through 2 years of calculus in HS if they want to. Obviously not every kid wants to, and they certainly don't need to, but if your kid turns out to be the math whiz, wouldn't you want her to go somewhere that gives her that opportunity, vs. finding out in 9th grade that her ES and MS didn't offer the courses she needs to qualify her for that track?) IOW, this is not just a one-year decision; you need to look at the whole K-12 process and figure out what opportunities your current ES would allow your kid to have later on down the road.
One of the things that can happen at these kinds of schools is that they focus so many resources on the kids who are behind that the ones who are already ahead are ignored and don't get the chance to develop. I'm not talking about things like fancy field trips -- really, who cares? I mean maybe they have so many remedial and ESOL classes that they don't have the resources to offer honors/advanced courses, or art, or band, or cool after-school programs, or any of the other niceties of many other schools. Yes, you can make some of that up at home -- but do you really want your kid to come home from 6 hrs of school to several more hours of make-up school? And would you really save any money if you had to hire someone to provide private art or music lessons? But the much bigger problem is just flat-out boredom: when your kid isn't challenged, she will get bored, and then learn to either tune out or act up. And whichever path she chooses, it turns school into total drudgery and squashes natural curiosity and drive to learn faster than anything else I know. (Ask me how I know).
Tl;dr: Don't be penny-wise and pound-foolish. Your kid is the most valuable "resource" and "investment" you will ever make. That does not mean it has to be fancy, but it does mean you need to protect her from something that is actively bad for her long-term best interests. As someone who is just about to send her eldest off to college, I can tell you with crystal clarity that my biggest regrets are when I did not act quickly enough to protect my kid from a bad situation, because I figured what we had was "good enough" and didn't see the damage until we were already down the road. I can always make more money, but I can't erase those bad experiences.
*Take your own influence with a grain of salt. Yes, again, you are clearly the biggest influence. But as kids get older, and particularly once they hit the teenage years, their job is to separate themselves from you, and so their friend group becomes more and more influential. You don't have to surround yourself with a bunch of rich kids, but it is very, very helpful if that friend group will have somewhat similar views and expectations as you do about education, college, etc.