On the redirect, an alternative is to move the align="center" from the TR to the inner TABLE.
My biggest problem with Opera and vB has been that the author column of showthread does not line up nicely. Two solutions:
The tables in which a post is wrapped have a TD width=10, TD width="100% - the spacer - then the inner table has two sets of TD width=175 and TD width="100%".
If people seldom or never use PRE text in their posts (vbcodes, code, php), replace the "100%" with a "*". Do the same with the Author, Thread heading.
However, this will not keep posts with PRE text aligned - in any browser that I've tried. With posts with PRE text, the only way I've found to keep the author column aligned is to put a spacer gif in the author column set to the desired minimum width.
The same also applies to threadreviewbit, which displays the thread at the bottom of a posting page.
Other than those few things, vB works fine for me with both O5 and O6 and O6 really rox.