I do not agree with separating the data collector and the data analyser. Potential pitfalls should be acknowledged and more rigor should be applied to avoid them.

Inconvenient I agree, but if you can find/are an operating system admin, you can take control of the file and assign whatever priviledges you like to the detached file. This...

I have used the alter database ... with rollback immediate extensively, it works very well.

However, there is a gotcha with set single_user. I started off using the set single_user...