And we are glad you did too, MamaDoolittle! I found the same thing with my chicks. Strong, curious, independent, and feisty, just the way I like 'em!
I've had many private messages from people who are embarrassed, or even angry, because they didn't get it to work well for them. So here, without naming names so they don't feel funny, is the main thing I think causes the issues - and I firmly believe that all of the issues can be traced back to this one thing - "the chicks don't behave the way all of my other ones have."
Chicks raised under MHP simply do not act like chicks raised under heat lamps. Ever. In any way. They don't waste energy running all over the brooder constantly. They are content to mosey here and there, exploring, eating, drinking and interacting with each other. They are so calm they seem almost like there's something wrong. They rest often - sometimes under the pad but most often on top of or near it. While we worry that they aren't warm enough, they are most often just fine. We are just used to sticking our hands in a heated brooder, worrying about thermometers and feeling the all over warmth, while they naturally just want to warm up for a few minutes or so then go back out. But we get anxious when they aren't always in the cave when we check on them and we just keep shoving them back under. They don't need us to do that. Maybe one or two need a little guidance to find the heat, but that's true with a broody hen too - we've all seen or heard of chicks that get separated from mom. For the most part once they know where the cave is, they'll use it when they need it. They usually find Mom when they really need her and take care of what they need. They cuddle with each other more.
They don't eat 24/7. They eat when they wake up, and throughout most of the day, but at night they sleep, in the dark, somewhere around each other and/or the cave. They get what they need, but not running around all day and night long they don't need as much because they aren't constantly expending energy. Their little bodies get a rest time, just as they would with Mom. She certainly goes to sleep at night and isn't up feeding them in the dark.
In a lamp heated brooder you'll often see a few here, a few there, but usually with some separation between them. We've heated their entire environment instead of letting them depend on scurrying under Mom and snuggling with the other chicks. With a broody they'd cuddle, either under her, around her or way over yonder. With the ability to regulate themselves for warmth, they don't need us as much, so we do lose that one-on-one that a lot of people seem to want with their chickens. They are independent. So they don't run to the brooder edges and cheep frantically when they see us coming. It's more like a "Oh, here's that big person again. Wonder what she wants this time." and then they continue to go about their business. So if you want your chicks to grow up being birds that run to you with joy every time they see you, you have to make an extra concerted effort to make that happen. @azygous is particularly good at that.
So I think the biggest reason people try this and just can't make it happen is that they are not seeing these chicks as broody raised chicks. They are used to the usual behaviors and when it doesn't happen with MHP, they get worried and either go back to lamps or just plain hate the whole system.
I'll be the first to say that this is not for everyone. In fact, I've made that clear from the beginning of the thread. I've said that if you don't think this is right for your situation, then by all means, do what you are comfortable with. There's absolutely no shame or failure in that at all. It takes a huge leap of faith to chuck everything you've learned about raising chicks and change it so dramatically. So for those of you who have taken the plunge and love this method, sharing with everyone else your photos, your experiences and difficulties, I humbly thank you for trying this. For those who tried it and either didn't like it or just couldn't make it work, I applaud you for your efforts and I understand completely. And for those of you just thinking about it with Fall Chick Days happening in so many areas, you could well be in for the chick raising experience of a lifetime! Congratulations.