Henrik,

Logical fragmentation means that your data is not in the expected logical sequence in each data page. This is generally not the most efficient way to store data.

Yes, it is usually a concern but not always and to varying degrees. As in many database related issues, it depends...

Logical fragmentation, what is tolerable on your server, and the best way(s) to respond to it can be complicated subjects because of the various causes of the fragmentation and the frequency of its recurrence.

I recommend that you study Books Online to get a good understanding of logical fragmentation, the causes of it, and then look at the fragmentation in your databases and the causes of it. From there, you can make intelligent decisions about how best to respond to it.

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I liked your solution for physical fragmentation (rebuilding the indexes into a secondary partition). I hadn't thought of that. I think it's a good solution.