I only have two bantam hens out in my flock and I get 2 eggs a day from them sometimes, but usually at least one every day from the bantams. When my chickens all started getting sick a couple months ago, the only one that kept laying was one of my bantams. I guess partially it does depend on the breed, and yes their eggs are pretty small. One of mine lays eggs that are just a touch smaller than my standard hens. I sell our eggs, and I keep the bantam ones for our personal use. We don't eat a whole whole lot of eggs, but the two bantams produce enough that I don't really have to use any of the normal sized eggs when I do cook eggs.
I really don't know why I bought bantams other than I think they are adorable. I have one bantam that broke her leg that lives in the house right now until I get her a more secure outdoor area built and she has only laid about 10 eggs in her entire life. But I think her broken leg healing kinda delayed her laying, then she got diarrhea and that set her back again. But hopefully she will start laying again soon.
If you don't eat half a dozen eggs every morning, I think you would be just fine with the bantams laying, especially with 4 of them. I think 1 a week would be worse case scenario. Even when all my chickens were sick and stopped laying for several weeks, I was still getting at least one bantam egg a day. I have a tiny sebright mix looking bantam hen and she is the one that I believe lays the larger eggs of the two bantam hens, so don't let their body size fool you. Some of my standard size hens lay huge eggs, some lay eggs on the smaller side, and sometimes the bantam eggs are almost as big as the standard size eggs that are smaller, definitely larger than a quarter!