I have two remarks and one question:
1. This realy sould be in the FAQ!!!
I think the FAQ should explain clearly that after 
pressing 'update' once you will have to rescan all the 
(potentially BIG) remote site before using "Continue an 
interrupted mirror" to try again fetching the few bad pages.

2. "Continue an interrupted mirror" is realy missleading 
name for "Continue an existing mirror without update".

3. Is realy only the local mirorred files are used and no 
existing files are downloaded when using "Continue an 
interrupted mirror"?