PC1: Mozilla 1.7.8, IE
PC2: Mozilla 1.7.13, IE
I run BMB on PC1, input both Mozilla bookmark files and export to all four destinations.
No errors reported on merge, and all additions, deletions and changes made in either Mozilla get reflected in both IEs, but not in the other Mozilla.
The timestamp on the Mozilla html files is updated on each synch, but the bookmarks don't change (except for the first time I populated PC2 from scratch using BMB).
The current version of BookmarkBridge wasn't designed to syncronize bookmarks between separate PCs. If I can find the time, a future version will support this.