>PMFJI -- here are the main advantage and disadvantages. The disadvantages are GUIDs take up more space and are slightly slower to process, neither of which is a major issue IMO. The advantage is GUIDs are guaranteed to be globally unique (that's what the G stands for), which can be important if data is spread across servers.

I'd like to see some numbers here - e.g. the performance difference with numbers. I guess they are available on the net and probably even here in UT, but may be you or someone can provide a direct reference.