That's a very sharp e-bike build you've got there BikeSlob. Something to be proud of for sure. And yes, I agree that a decent e-build will run a least a thousand (mine came in at just over $800 due to a "$200 off sale" on the motor kit). Must say that it's good to see that you're not using a "hose-clamp" torque arm on that beast.
As for water-proofing the wires where they go into the pie; if you can, make sure that the wires "drop down" a bit (below the axle) before they go "back up" and into the axle (this will help keep water from collecting on the wires and then following it down into the axle). This, and the application of a good sealant (like what you have) will do much to save you from having water enter that pie of yours.
Btw, do keep a very close "eye" on your spoke tension (especially during the first couple of hundred miles or so (mine loosened up more than a few times on me). Same goes for the pie axle (and everything else for that matter).
As for water-proofing the wires where they go into the pie; if you can, make sure that the wires "drop down" a bit (below the axle) before they go "back up" and into the axle (this will help keep water from collecting on the wires and then following it down into the axle). This, and the application of a good sealant (like what you have) will do much to save you from having water enter that pie of yours.
Btw, do keep a very close "eye" on your spoke tension (especially during the first couple of hundred miles or so (mine loosened up more than a few times on me). Same goes for the pie axle (and everything else for that matter).