multiple databases or not?

[redflux]

I am interested to know how UR users organize their information. Do you:
a) Have one big database and have lots of different Info Types, or
b) Lots of databases each with one of two info types?

Are there advantages or disadvantages to either approach. When reading the the "pitch" for UR, it seems to focus on:-

"Instead of maintaining parallel sets of information
segregated by their type or source, you can organize notes and data by linking them all together logically in Ultra Recall."

..which makes sense, so why would i have separate databases for separate stuff?