I like modeling in NVil more than modo 601, silo or my old 3ds max.
There isn't much in the way of training, but I found that referencing the Smart Tips panel and fiddling around it's not hard to figure out. If you are familiar with other poly modelers the routines are pretty standard. It's also worth while going through the Modeling section of the NVil Help.
I was pretty excited about the silo update too a while back. Unfortunately it's still riddled with instability. I've experienced far too many fatal crashes with even 2.31 to be able to use it comfortable in the knowledge that I wont lose work.
investigating Nvil now again just for the fun of it:)
I installed the Silo update to have a look. After I installed it I kept getting a message to back up my encrypted certificate. Never seen that before, so I uninstall it.