The ones in our area are about as proportionally decent as the rest of society. Some good, some bad, some a pain in the ass.... They're losing membership quick as a lot of the kids leave the church. A lot of that has to do with farmable land being developed for housing and the remaining propertys sell for more than it cash flows so they just can't farm.
Most of them get into construction of one kind or the other. I don't personally know of any that build unlicensed or uninsured. They can be hard to deal with when it comes to business most of the time, trying to squeeze every dime they can. Most aren't the brightest but not surprising since they leave school at the 8th grade, but some, like a family I know that owns a machine shop will amaze you.

The kids outwork 95% of other white kids their age, and that's a fact. As far as a labor pool, for construction type work, they're near the top. As far as my interaction with them, two neighbors, my metal roof guy, my mason, guy that repairs my tools, guy I buy my stocking trout for my pond from, guy that repairs hydraulic cylinders on my equipment, guy that owns the archery shop we use....
All Mennonite, no Amish in this area to speak of.