I love that you focused on commodity parts. That is excellent, I really like the placement of the system. Do you intend to take it trails riding? I would just be careful of those XT connectors and be mindful that you've reduced the clearance when traversing over ledges or rocks by moving the lowest point farther forward (you'll hit it quite a bit sooner essentially).

I also love that it's internally geared, I've always felt this made way more sense for mountain bikes anyway given the weather protection. Good stuff!