Thats probably more to do with debian being lighter-weight than ubuntu than sysvinit vs upstart. Ubuntu starts a lot more services and such, whereas debian has a more minimalistic approach.
I kinda suspected that. I haven't tried removing services or building out a minimal install because I have no interest in running Ubuntu full time; I just like to keep up with its development and try new releases because it is very popular and closely related to the distro I contribute to most heavily.
I would agree that systemd improves boot speeds better than upstart though, its got a more modern design and better parallelization (socket based vs event based). But I'd also say upstart > sysvinit too.
That's interesting. Why would you say that? All throughout the SysVInit vs. Systemd debate in Debian and elsewhere I have not heard anyone offer an argument (not to mention a convincing argument) that Upstart is superior to Systemd. The best justification of Upstart I have heard yet is that it preceded Systemd, so Upstart is justified being in a less advanced state. Even then I have not heard an argument for its adoption outside of Ubuntu, although some argue that it is acceptable for Ubuntu to stick with it by virtue of the fact that it is already in place and migration would be an unnecessary hassle.