I know it's been a while but I finally got around to sending v1 of the GPSDTx board to the fab. I used Elecrow again as they are consistently the lowest cost for up to a 10x10cm 4-layer board with a solder stencil. $100 for all that and it will be at my door in about 10 days from when I submit the design. One sad thing is they are now charging $5 to have a board color other than green (the different colors used to be all the same price). Anyway, I'm looking forward to getting this in, populated, and running code.
Aside: if anyone knows how to easily and efficiently implement USB on the STM32F4s, I'm all ears!
As always, the DipTrace files and gerbers are on Github. If you look immediately when this log is published, look on the branch develop. If there is no develop, then I have already merged into master.