I run ML on my 50D with no issues. I do use quite a few of it's options too, even though I'm only shooting stills.I find the Manual mode EV lock to be very useful, since like in P mode you can have the exposure level fixed, and quickly change the shutter speed/aperture/ISO combinations just by spinning the dials. If you run out of aperture or shutter speed then it will change the ISO instead. Really useful at an airshow when I need to quickly change from 1/30s when trying to get helicopter rotor blur to 1/2000+ for a jet aircraft. I also use the DualISO feature for situations where higher DR is necessary. Some of the focus stuff looks interesting too, but not such a help to me, although it does offer automated MFA using the DotTune method.
I have been running ML on my 50D since I got it back in 2014. Before that I had a 300D from 2005 to 2012 that I ran with the "Russian Hack" 10D firmware from when the warranty expired. The 300D failed due to a mechanical failure of the AF submirror pin, so nothing to do with the hacked firmware. Certainly if you are not really pushing the overclocking type options I don't think you have much to worry about using the ML firmware. The large disclaimers about bricking the camera seem more of a CYA process at this point.
Alan
I'm a ML fanboy
I really like the expo lock as you mentioned, I use manual exposure about 95% of the time. I also use:
Long Exposures in Bulb -- you set shutter speeds exceeding the 30 second exposure limit in the camera.
Highlight Clipping -- I'm very partial to ETTR and am able to see when the highlights are getting clipped.
Dual ISO -- gets used quite a bit. This with Highlight Clipping gets you about as much DR as the camera can handle!
ML is quite strong in the video side, which I never use. The few features I use make the camera a real joy to use. Mind you, through the years I have used many different types of hacks for work and pleasure(other than ML, none related to photography) and have never had any issues with bricking the hardware. As mentioned before, the disclaimers are for CYA purposes. I actually have quite a bit of respect for those that provide the hacks.
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