I agree with Lopho here... They should put out an LTS *BEFORE* QT5 is released so that people who want to wait out any painful transition period can. QT4/KDE4 was fairly painful in the beginning (4.0,4.1). A lot of people would rather avoid having to deal with that, and would rather just pick up QT5 after it's been thoroughly tested/debugged. This means waiting until a few point releases have come out.
On my personal systems, I have no problem going with the latest and greatest (Currently running GS on 11.10 on my desktop/laptop and Mythbuntu 11.10 on the HTPC), but on my work machine, I'm a lot more careful about what versions of software I upgrade to. My boss probably wouldn't like it if my upgrading to the latest release of something prevented me from working for a couple days while I backup/reinstall/downgrade.
I dunno i'm sceptical about Kubuntu. The current releases installer has a bug that causes the partitioner to crash when faced with complicated layouts. This type of bug in a stable release tells me they probably don't have the manpower to test the distro properly. Maybe for LTS releases they'll get more help though