I am raising booklice (I thought they were springtails), but which are really similar. And I have raised springtails before, but not to a large number as you have. So while my experience is with booklice, because of how similar they are, I think it still fits.
Booklice have been completely harmless to my Pogonomyrmex rugosus. There are thousands of them in their formicarium as well. Though I DID see a single booklice attach itself to a worker like a mite would, but it got off right away. It looked like it was defending its food. That was just once, and a while ago. Ever since then, they completely co-exist. They have cleaned up a lot of mold and kept the formicarium really clean. I haven't had any issue with them eating ant eggs or anything like that.
And supposedly there is a post I found on a...well..."weed" growing forum. This was a couple years back. I quickly got off the site because the forum had infected ads that kept being blocked. But, supposedly springtails eat mite eggs. Not sure if that is true or not though. But, if so, that is a HUGE benefit. They "supposedly" don't eat the mites, just their eggs. Which if true, is a huge benefit to raising them. Booklice in my case probably have the same benefit (if the guy wasn't lying or mistaken), just because they are so similar.
Other than that, I've never heard of any issues with people having large amounts of springtails or booklice in their formicariums. Drew even raises cultures of booklice (maybe springtails too?) for his formicariums.
Plus as an added benefit, if you get certain types of frogs they eat springtails. 
Makes it a good food source if you wanted to keep other stuff. Not sure what else eats them.
