We got the first batch of replacement MXL pulleys today, and they are excellent. They seem to be exactly the same as the pulleys from buildlog.net, and slightly better than the ones in our batch 3 Inventables ShapeOko kit (although those are very good too). The grub screws are metric (M3, with 1.5mm hex sockets).
These will go in the kits ordered before 1am on 2 October. Orders placed after that will have to wait for the next batch, due the week of 22 October.