Yes, you are right on both counts.

@This is not mirroring:
Yes, this is not an exact copy of the original. But then as I mentioned
earlier, the very idea is to edit the ripped contents (or at least to add
comments). Thus this can be considered as a separate product, forked out of
WinHTTrack. It can be released as a plugin for OOo.

@format of individual pages may be different:
Almost all sites provide "printable" version of their pages. The "normal"
story may be spread across 7-20 pages. The printable page combines them all.
Can WinHTTRack do that? Even if it is not perfect, it would provide a great
functionality that is not available elsewhere. 

Thanks.