I am delighted to read your intent with this site.
While there are a few issues that I have with Linux as my productivity machine (mainly associated with a lack of familiarity) the killer for me is transferring over a decade of Outlook data to a Linux environment. This is not just a contacts list, but also calendar and tasks. These track everything from my hardware serial numbers to my medical records.
If that affects a single person badly, imagine what it does to a business, of whatever size, in confronting the move?
M$ do not have a particularly inviting solution with Outlook, but it was used at work so I bought into that package. At the moment I am faced with hand copying most of this information from Outlook to individual Linux products in order to make the move a permanent one. This is not a solution, it is a barrier.
By the way, the one advantage of Outlook (NOT Outlook Express) is that the data file can be backed up by copying it, and restored after a computer rebuild by copying the data file over the newly created one. Admittedly this is mainly needed due to the instability of M$ operating systems; but problems occur with all operating systems and so an equivalent of this ability would be welcome in any Linux solution as well.
I have mentioned this problem on a few sites; but yours is the only one I have seen that seems to really get the importance of this issue.