We tested kvm-qemu.git master. It turns out there are some command line options that will make Qemu perform better but we've yet to test them.
It's never going to be an apples to apples comparison but it goes to show how important _sane default values_ are. I'm willing to bet most people don't know about all the Qemu magic that makes things run faster (which is especially important for virtualized I/O).
And just to set the record straight: the only reason we did the comparison was to see how *badly* we'd compare against Qemu. Turns out we didn't do badly at all so there was no point in hiding our results - even if we have to eat our hats later on!
Disclaimer: I contribute to the tools/kvm project.