Well, I received my first Pi 4 yesterday. It's brand new so I had to do the step to make it USB bootable. Once I did that I popped in a thumb drive with the CDVR image and it came right up. WOW, it performs much better than I thought it would.
Even though I won't be using the CDVR app on the TV, I'm still going to play around with all the features eventually. But just serving M3U and the guide this thing is outstanding. Here's how it performs serving 2 HD streams pulled from an HDHR Quatro.