We are actually measuring systemd very frequently and compare it with what was there before. But I am a bit reluctant publishing those results, because I don't really believe they have too much value, since they are difficult to reproduce, and have little relevance on what people actually will experience.
The results range from one extreme (On an X300 on SSD we reliably can boot the full stack in < 7s) to the other (virtually no change if you have additional sysv services installed and rotating media). I prefer reading the bootchart measurements as a simple indicator where we need to fix things, not so much as something were we can people tell "hey, install systemd and your system will be as fast as this", because well it won't.
systemd is just a tool to make things faster. It's not magic potion you apply and which then magically makes everything go faster. There's not doubt that systemd is the right approach, but before we are happy with the end result we need to fix quite a number of other things all over the place. For example, one thing we learned is that maximizing parallelization the way we do has little benefit on the disk elevator on rotating media. Naive people like me assumed that providing the current Linux IO scheduler with a larger amount of requests at the same time it can choose from would improve its performance. Turns out it currently doesn't really. There are things one can tweak to improve the situation, but I guess we can safely say that the current Linux disk scheduler for rotating media is not optimized for this kind of workload systemd now pushes onto it during boot. (and yes, I hope to shed more light on this during LPC).
If you take stock F14 system on rotating media, you'll probably measure little difference from F13, simply since only a small subset of the services have been converted to become parallelizable and get rid of the shell (i.e. ship proper native systemd files). However if you run my development system things look much different because I did the full conversion, and the shell usage is very much reduced.
So, I guess what I want to say: consider this all work in progress. I won't stop people from measuring the boot times, but I am not planning to publish a lot of data in this area any time soon. Because I could provide you with both: graphs that show a super-duper speed-up and graphs that show virtually no speed-up at all. And both could rightfully be called systemd performance measurements.
Anyhow, I'd prefer if people would not reduce systemd to the speed issue. It's a lot more. It's an attempt do things the right way, to simplify things, and to make the boot a lot more powerful, for users, developers and administrators alike.