This. If they're gonna make a mess, they'll make it at a slower pace that'll give you ample time to correct whatever they're doing wrong. I'm no longer in the industry, but for almost 20 years, I preferred smaller crews for lots of reasons but mostly this one. As hard as it is to please landowners, it was almost always in my benefit to have slower moving crews so we could change/adapt as we went.
As for the WBs/BBDs, I would suggest WBs for side roads or skidder trails that will be at least semi permanently closed to vehicles. Much traffic at all will eventually make your water bars fail and will require rebuilding. On access roads or other roads that will remain open, BBDs will work better. Knowing how to build these structures is paramount. Water bars ARE NOT just dams across the road. This was one of my pet leaves. To work properly, they have to be cut in and angled down and out to first get the water off the road, and secondly give it a place to go. If your loggers just dam up the road with no thought to where the water needs to go, it'll eventually just fill up with silt and then the water will overrun the bar and wash right down the road again. BBDs need to be properly constructed as well. Ditches and turnouts along with the BBDs will keep your main roads in good shape long term. A little maintenance here and there goes a long way. A smaller machine with a 6 way blade is way better for building and maintaining water control structures than a big straight blade machine that is often used in road construction.