Hey guys thanks for the help! Still in the middle of the build and haven't hooked up my Rx yet, but pulled all the pins and swapped the white cable to pin-8.
Hooked up my oneshot/active braking esc's up and they started twitching when I calibrated them, so I dropped the min. output value to 950 and the twitching stopped.
Slim-builds are tough! This is my 4th slim iteration, but finally jumping to 4s.