It was inevitable. Despite Apple’s NDAs, some recipients of the Developer Transition Kit have uploaded scores to Geekbench (albeit only x86 benchmarks run under Rosetta so far).
Looks really good. It’s using a nearly 2-year-old chip (not bound for new Macs) that Apple underclocked by 100Mhz, running a development beta, running an Intel benchmark in Rosetta, in which apparently only 4 out of the chip’s 8 cores were utilized, and the results are still faster than Microsoft’s native ARM machine results.
This strongly suggests that a new chip fully utilized, on a finalized and tweaked macOS version, may end up being quite fast at running Intel Mac apps.