We did some testing recently. We used to use Office 2004. Office 2008 is not really that compatible with Office 2004, and has a learning curve (different UI) so actually no more logical upgrade for Office 2004 than iWork or OpenOffice / NeoOffice. So we did some compatibility, speed and UI testing and reached the following conclusions:
* iWork – easily most compatible (i.e. able to read 2004 files without errors), and easiest to use, and fastest in operation. But uses odd file format (folder based) that makes files huge (3x bigger than office equivalent) and requires them to be zipped before they can be loaded onto internet file systems or sent by Skype (something we do alot). Not very expensive.
* OpenOffice / NeoOffice – second most compatible, second fastest in operation and with most familiar UI. Does the job, but UI a bit rough around edges. We ended up testing NeoOffice which has best compromise between OpenOffice function and Mac compatibility. File sizes the smallest of all three applications – typically 2/3 of size of Office 2004 equivalent. This app is free.
* Office 2008 – least compatible (some of our old PPT files wouldn’t open at all!) and slowest in operation. Least liked UI – but possibly this could be tweaked to be less annoying. File sizes slightly bigger than Office 2004. This app is very expensive.
So we have ended up moving to NeoOffice – which is free (so no dodgy piratebay activity required). Works pretty well.