I think variability is the key here. It sure seems like there is a lot of variability of these engines that use a Makita cylinder and piston. Without looking at a large sample of engines from each of the manufacturers we really can't draw valid conclusions about which one (on average) is more powerful. On the other hand, if one of the manufacturers produces engines that always tach within 100 rpm of each other, then you don't need a big sample size to have faith in the numbers. Do you think any of these guys wants to publish the typical rpm and include a standard deviation and the number of engines tested? Ask the Taurus boys and see what they say.