This is just an initial reaction, but perhaps the KDE community should consider making Calligra the standard.
Koffice is horrible. I've had it crash on me simply typing up a report, without changing fonts, font sizes, nothing. Just open application and start typing.
At first glance, Calligra seems better maintained. According to:
http://www.koffice.org/kivio/ Kivio needs a maintainer.
To all the flamers: I'm not saying that Kivio is better than or worse than Flow. What I am saying is what's easily observable. An unmaintained program(or package within a suite) doesn't have a future, and does threaten the suite as a whole.