The end mills came in today, they work much better than the other cutters I had, this was cut using a 0.011" 4 flute end mill. Once the engraving bits come in I'll do a comparison between them to see if there is a significant difference. The end mills are quite a bit more expensive than the engraving bits, the end mills I got were $6 a piece on sale from $23 and the engraving bits can often be had for under $1 a piece.
I didn't get a great deal of time to work on this project in the last couple days, but I made some progress on the GRBL electronics to replace the RAMPS board. I am aiming to build a "shield" for the RaspberryPi that will have an ATMEGA328 and 3 stepper drivers on it and plug into the gpio header. The atmega and RaspPI will communicate over the serial port on the gpio and I will hook a couple of the gpio pins to the atmega for feedback and so the RaspPI can program the atmega. I believe I have all of the components in the schematic and the layout is probably about 90% done.