I agree. A12z was not really meant for desktop run which explains low base clock speed. Hopefully, their Apple Silicone will be much better.Its not too bad! I mean, already this dev box under Rosetta seems to be competitive with the native MacBook Air. By the way, I'd expect that Rosetta-translated software will run better on the final hardware (it probably will contains some additional hardware support for this kind of utilization).
I got the email today to order my kit - unfortunately it won't be here until the 1st week of August, but I'm ready to see firsthand how MacOS runs on ARM code.