We actually have a couple users live on Scrypt right now using Nicehash and have had dozens use it over the last several weeks. I actually wrote a quick article on the main site to explain it, located here. There is even a picture of the connection details in the article which should be helpful.

As far as Nicehash for sha256, I have not seen a live user try it out yet, but the pool seems to pass the verification when I try it out using the same details except the sha256 port number and the recommended difficulty of d=1000000. Originally the sha256 difficulty of our pool was too low to play nicely with Nicehash, but it has since been adjusted and their pool verification passes our trial attempts. We'll probably give it a spin ourselves soon to ensure everything is also fine.

Going back to your other post, we don't necessarily see as much info about your devices as you do in the Antminer control panel. That being said I've seen many people on forums throughout the past year say that a set difficulty of 128,000 seems to be the sweet spot for the standard L3+ (assuming no Overclock of the chips). Personally I've tried a set difficulty of 128k and var diff and both seem to be decent when the pool sets a close value to that. Essentially the coin offerings, job size and other variables play a bit into what diff number is "perfect". If we get better info than what we have now, we'll be sure to update appropriately.