Having looked at 650B bikes recently the one question that I needed to resolve if I went with the less popular 650B size was what tires to use? If they stopped making 650B rims I could buy 8 and be set for 20yrs, but tires don’t last that long and don’t have the same shelf-life as a rim. Having said that the Greenspeed Scorchers have shown me that you really only need one awesome model of tire for a given wheel size to be happy. So I don’t care about having 15 choices. I just need a couple awesome ones.
The Pari-Motos are 127TPI & 280g with a true width of 38mm sold by Velo Orange for $59USD. They are very thin which makes them light and fast, but not very durable. Jan Heine at Bicycle Quarterly calls them an “event tire” because their thin casing [1.3mm compared to the 2.3mm of the Hetres] will wear out in ~2000kms on the rear. The Hetres are 412g and 42mm wide sold by Compass Bicycle [aka Bicycle Quarterly] for $68USD. The more robust Hetres hold 16% more air and should last over ~4000kms on the rear.
That sounds like two great options to me. Pari-Motos for brevets where speed/efficiency is key and Hetres for training and general use where long life and some extra plushness matter more.