Medium and hard mode are nowhere near as flexible as as uMatrix. It's good, but it's not uMatrix.

I’m willing to put up with if it it means gorhill will have the energy to maintain just uBO instead of burning out entirely :)

Definitely! I'm going to keep using uMatrix until it starts getting in my way, but otherwise uBO will do.

Could you elaborate as to what the specific differences are?

For starters with uBO you can individually block types of requests (images, js, css, cookies, frames, "other") per domain and/or per subhuman.

*uMatrix, not uBO

And subdomain not subhuman :)