I've been growing N. lowii for a while now as an intermediate and it's actually settled in faster than any of my other Neps. It also isn't all that slow, which is odd considering all the fuss I've heard about it.
Now on the other hand, I've been having the hardest time growing N. inermis. I do think it's due to some overwatering on my part though, so I'm letting it dry out a bit before it gets any more.
Perhaps one day I'll get Nep watering right. It's such a problem for me