I got ML on my 60D, and I have found that it comes with nothing but advantages. I haven't used it much other than the intervalometer which is great for time lapses, and focus peaking. The additional ISO settings are extremely helpful as well. The cons you're worried about are things like bricking/crashing the camera, right? I have had it for about a month and I've experienced no problems. I can't guarantee that it'll be 100% safe but it's fine for me. I don't even know why they call it a "hack". It's rather a firmware extension, IMO.
Hello future me,
I had no expectations for you. So anything you have done is a plus for both of us. Good job! -iAfterBang