Interesting about the Kumu drums. I'm going to look into them. That was another question I had whether the use of scandi birch was the way to go. I took that into consideration when I bought my SQ1s. I'm very happy with them. Not sure what birch Yamaha is using now and the flimsy hoops were a turnoff to me. This thread was as much about who is still making birch kits as to what are the good ones.I'd rate Kumu as more than up there - pretty much the bar standard in Birch drums IMHO. Let's put it another way, if I wanted a birch set, I'd buy a Kumu before anything else.
BTW, when considering used / readily available options, another vote here for early Yamaha recording custom. They pretty much epitomise what a standard production birch set is & should be. I don't have sufficient direct experience to judge the latest RC offerings.