1.) No 4K 60p and windowed 120fps. The Ursa Mini has the same windowing issue as the C300 (though UM46k CAN do full 4.6k 60p). The FS7 does full frame up to 180 fps, but had a number of other issues that ended up disqualifying it.
2.) Cost (after similar base packages are built it would have been $3,000 more than the UM46k).
3.) Non-ENG shape. I liked the idea of having a handheld form factor with a minimal rig, but truth is I usually am shooting on a monopod, tripod, or gimbal. Shooting on the shoulder doesn't come up much with the work I do, and is always available via a rig in the future.
RAW isn't that important because the C300 II still has great latitude and a very clean image, with the ability to output raw externally in the future if I wish. I really wanted that full version of Resolve but the free version is great enough for now. I really wanted internal ND's and autofocus. Events and corporate stuff aren't my passion but they pay the bills.
Finally, name recognition and perception of reliability. I actually spoke to Lens Rebtals after this post and they said, though the Ursa Mini has gotten better, they still have enough issues with the ones they rent out (Fixed Pattern Noise, Dropped Frames, XLR noise) that they cannot recommend them for professional use. That is a big factor. A big part of buying a camera can be, how likely are people to hire me AND my camera. I don't want to have to convince clients that it is a serious camera (and it really does look like one, but it seems like it isn't quite where I want it to be for such an investment).
Again, I thank you all so much for weighing in!!