Just circling back, the lens is great as expected. I do find the zoom very useful, more so than the 300mm prime would be. Looking over the EXIF from that evening, focal lengths ranged from 135-300mm, was great to be able to capture a small group then zoom in on individuals. I was typically between f/2.8 and f/5 and for almost all the shots the ISO was 6400 or less, which is a comfortable place on the R3.

As a nice bonus, the TT DH-150 holster has a small side pocket for the rain cover. With that removed, the pocket holds an RF 24/1.8 (with hood) for a wider FoV. Of course, it would also hold either the 1.4x or 2x extender (for which it was likely designed by TT), and that's good for other use cases.