Using a TableHeader Vs Using the Page header in XSL:FO

Dear all.

I was trying some stuff and realized that the document headers can be
either used using the region-before or using the table-header.
The later is by not having a region-before, but define the region body
as a table with the first row as a header row. I know that the
following arguments goes for the  region before
1.region before is designed for page headers
2.there is a code separation where we can clearely see where the body
if the page is and where the header is..
3. In a page where there are no tables, you would have introduced a
table for no reason... etc...

May be some more.. I am not trying to clearely use the table header
instead of the page header, but want to know if there are any
performance benifits in the page header as opposed to the table
headers? And is there a situation where we can definitely not use a
table header ..

Vasu