I got a friend of mine to try some loud WOOOs with one of his 6060s at his chest, transmitted through an MTP40S, in a quiet environment.
Here it is on a spectogram. Each yell is slightly louder than the last, and it is as clear to the ear as it is to the eye, that it has this fuzzy noisy distortion coming in.
It doesn't sound like harmonic distortion, but rather like the overloading of an old webcam microphone.
I'm not 100% certain that this is coming from the 6060, but I would think the MTP40s preamp would distort by adding harmonics, not this noise stuff.
It certainly didn't clip digitally, though, so it must be one of them.
His yell seemed extreme in that quiet environment, but if he was next to a busy highway or something, it might just seem like a slightly above average yell.
And I think any level of raspiness in a yell like this would mask the distortion. Put that in a less silent environment, and maybe it won't grab your attention. Maybe.
Considering this test, I'm now happy to report that it seems both my fears are true. There is a reason these two are separate microphones, made for different circumstances. Great.
Personally, I'm more scared of the noise floor, than I am of the noisy type of distortion I hear in this test. So I'm starting to lean in the 6060's direction again.