I've been using that technique for a while. It's great for most areas.
There is one caveat I learned about this weekend, however:
Walkmesh helpers trump the non-walk spaces, and walkmesh cutters trump the walkmesh helpers.
So if you have a really complicated walkmesh area, the best method seems to be to use one big walkmesh helper, and then cutters. and forget about the non-walk areas. Because the walkmesh helpers will override them anyway.
I have a really complicated walkmesh in one area with a lot of docks, Heed's boardable ship, bridges, and a connecting ramp. I tried a lot of different ways to bake it and a lot of different configurations of walkmesh helpers.
You might expect the non-walk areas to get obeyed no matter what, but this is not true when the walkmesh helper overlaps the same space.
So, with a complicated area, what I learned was the easiest method was to make one huge walkmesh helper, and then use only cutters to defined the non-walk areas. And of course, set all docks to environmental objects, etc.
Doing that, I was finally able to get a decent bake.