@keel - for the SD hack I used files from @Danne's bitbucket page: https://bitbucket.org/Dannephoto/magic-lantern/downloads/ (I hope it's ok to share this, if not I'll delete the link)
I downloaded the "magiclantern-Nightly.2018Apr17.EOSM202_sd_uhs.zip" file from 17th April 2018 and put that in my card (not the 27th April file which wouldn't do anything when I tried to run the overclock test). Then I downloaded his sd_uhs module file from 19th April and put that into the modules folder in ML (replacing the sd_uhs module that was already there).
After that I followed @IDA_ML 's instructions on how to run the SD overclock test and the card benchmark test, ensuring it's all done in photo mode. His instructions are here: https://www.magiclantern.fm/forum/index.php?topic=16040.msg200229#msg200229
And it worked. I used a Sandisk extreme pro 95mb/s 64gb card. I'm only shooting 24fps.
Do let me know if there's a better way to do this!
This was exactly what I did originally, and now all I changed was the build date to Walter's recommendation (and I moved the sd uhs module, unless there is different iterations of the module and i used an incorrect one but the module runs, and my recording crashes. Sounds like user error and I am loading something incorrectly related to raw video)
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UPDATE: i have made a bit of progress,
i was confused about the various modes (movie crop/crop mode/zoom)
especially coming from 50d, that zoom feature on the touchscreen of the eosm went over my head.
After closing the other modules for crop/raw to experiment i found it started to work a bit with MLV lite instead of 2.0
(im sure this is said somewhere in the threads, i may have missed it)
Highest I got on two cards was around 41mbs 2240 X 954 (3.74X) 2.35 12BIT
Highest bench was 45mbs write. This really boggles my mind because I was expecting some great performance from these Lexer Pro 150mb/s 1000x cards. Even a bump to 56mb/s seemed feasible, but I am stumped.
Again, I assume more often than not, user error.