Here's the IRC logs of the decision to delay SystemD, and some well-informed comments of reactions.
http://lwn.net/Articles/405100/
Some of the bootcharts show readahead-collector running, one shows an ext4 fsck. Perhaps they don't make much difference to the results but they don't inspire confidence in the testing methodology.
SystemD is about daemon management. Launching, restarting an restarting them. Benifits are more stability in case of a daemon crash; self-healing capabilities without restarting other related daemons (dependancies).
SystemD also only leads the bare nesecary daemons, meaning less RAM and CPU usage; the bare minimal and on request, so you never have to start a daemon yourself.
Just one of the advantages is faster boot times due to bein able to launch multiple daemons at once, even if the have depencies. This is also useful for launching daemon during runtime.
I did noticed Fedora 14 still uses hald, which is deprecated and it was the last/slowest to start up completely, Ubuntu 10.10 doesn't load it anymore on a default install.