I pulled out 3 ooths from my primary colony of N. rhombifolia to see if they'd hatch at room temp (67-72). I kept the humidity pretty high (part of the paper towel they were on molded up a little.) After about 2 months, they finally hatched. (The others, kept at nearly 90 degrees, hatched possibly 2-3 weeks after being laid!) There are quite a few babies (only 2 ooths have hatched so far) and I believe the other ooth will hatch soon too.
I know many people are having trouble with this species; my best advice is to warm up the adults to increase production and keep the humidity very high.

Good info, I think the problem I had was low humidity.

Ugh! Now you guys are making me want to try them! Knock it off will ya?! I've got enough species. Well, I guess there always room for one more... or two or three... I did just build six new bins to have around as extras...

Great experiment. Thanks for posting that.

When I had them, I kept a piece of plastic wrap over the top of the critter keeper between the container and the lid with some small holes poked in it, and had a couple successful ooth hatchings even at room temp.