Hello Kevin,
there are a lot of "ifs" to fill in with that question, in order for us to be able to properly answer it.
1st: when you say "averaged sized" that could mean anything. an averaged sized polyspilota griffin ooth could hatch 150 mantids. and an averaged sized moments binotata ooth could hatch 20... So please clarify the species of ooth you mean by that.
2nd: when you say 1-6+ species. that could mean 1-6 mantids(1 each) or 700 mantids(hundreds of each species).
3rd: All mantids(past their first instar), with proper care can make it to adulthood. thats not to say that there won't be any random die-offs, but there is always a reason (lack of proper humidity for that species causing mismolt, the mantis deciding to molt off of a ledge or branch and accidentally falling, parasites in the feeders, stress, temp issues, etc.) we may not always know the reason, but there always is one. Just make sure you know the proper care requirements, and stick to them, and you should have no problem getting your pets to adulthood.
if you could clarify on the first two, then id love to be able to give you an accurate answer.
get back to you soon-
Ethan