First off, since people are concerned about speed in the first place, I think it is reasonable to assume that the Hurd isn't targeted as a research OS (unless we're researching speed, I guess). I also don't think the single-user desktop is the intended audience either, since there's only a minimal amount of tooth gnashing about bloated programs like OpenOffice and Mozilla running on top of GNOME (or maybe Squeak would be a better example in this case). So I think it is relatively safe to assume that the Hurd is gunning for the multi-user server OS market (flame away!).
With that in mind, I was wondering how exactly we should measure measure the speed of a kernel to determine if it is good enough. On the one hand, you could gin up some microbenchmarks which try to compare something goofy like the number of kernel calls you could do in a second. That may be okay if the two OSes we are comparing have similar designs. But the whole point behind a new OS is that it should be doing some things differently. So maybe we should measure something more useful, like how big of a load Apache (or some other userspace program) can handle running under each OS in question. That's getting better, but if our new OS is different enough, why would we expect to get optimal performance from an application which wasn't specifically written to take advantage of its unique features. So maybe we'd really like to compare application categories (like web serving) instead of individual applications. But then we start to lose the apples to apples nature, and people will complain about unfairness and saying you shouldn't measure performance in this manner. So why were we caring about speed so much in the first place?