At the very first: ML is very great stuff and is a great ingenious work! Its an overwhelming thing, can't say thanks much enough! It makes a lot of fun playing and working with it!
Right now I'm playing with ML on the high res end.
I confirm that 3.5K works continously at 2.67:1; 12bit lossless
WOW........ @a1ex you did it. I just tried the new build, it recorded @ 3.5K 12bit Lossless 2.35:1 continuously.. Zero Hick-ups so far. Converted the images with no problem they came out beautiful 
@goldenchild: are you sure that you managed real 2.35:1 with 3.5K?
3.5K @ 2.35:1 (3520x1498) only 14bit lossless is supported with this vertical resolution and here you end up at >105MB/s at 50% compression --> not continuous
Also 1320pixel is max vertical resolution for the 5x crop mode (3.5K 1:1 centered x5 as well as 5x live view crop) and this is currently the max. vert res for 12bit lossless and lower
By the way I tested 3.5K 2.39:1 at UHD crop mode to get a vert res >1320 but at 14bitlossless. Depending on the brightness of the image I manged to get 120 to nearly 200 frames in this resolution.
Here is a quick test:
https://1drv.ms/i/s!ArsIFng0eZ9dgYhqj9iycEK3sGsFSQ3520x1472; 14bitlossless; 23.976; UHD crop mode --> ~105-110MB/s
ISO 400 --> 120 frames
ISO 320 --> 150 frames
ISO 200 --> 186 frames
as mentioned above 3520x1320 works continuous due to 12bit lossless capability, but is 2.67:1...
By the way there is a small bug:
when accidentally entering the UHD crop mode from 3.5K (where 5x lv zoom + fps override to 23.976 needs to be enabled) at a resolution of 3520+ the FPS override changes to an odd 33.. fps speed. When turning fpsoverride off it changes to 19.. fps. While turning off, the Picture Style window from Canon menu flashes up once.
To eliminate this you need to turn off crop mode und raw video, close ml menu and turn everything on again (without x5 live view zoom + fps or!)... Nothing substantial but a bit confusing.
Can anyone confirm this?