Not sure what's going wrong here. Initially I was using a basic SD with a write speed of 13mb/s (tested with internal benchmarks). I was getting a frame skip error so I got a 32gb UHS with a (benchmarked) speed of 38 mb/s read and write. However it's still giving me the same issue when recording raw footage. The files it outputs are extremely choppy, probably around 12fps. Does the 70D have a limited write speed or something? Is that what's forcing the camera to stop recording?
addendum: I'm trying to record at 24fps with a resolution of 1824x1026
addendum 2: I believe I've solved the problem by using arczipl's Mar152019 nightly build. I'm gonna go out and shoot some test footage but it seems to be functioning properly at the moment.