I came across a practical problem while using tabu: one of my tables requires to change the vertical spacing mid table, for example the first 6 rows with spacing A and next 4 rows with a shorter spacing B. I would like to use \tabulinesep, but it sets the spacing consistently for the whole table. I would rather want to set e.g. \tabulinesep=2mm an the beginning (like usual), but then change to \tabulinesep=1mm after some rows and keep it for the rest of the table. Right now I do it the "dirty" way, but just using that fixed \tabulinesep=2mm and then adding [-1mm] at the end of every row that I want the shorter spacing at. But that's not very elegant and also, when my table is colored, you can see the overlap caused by the shift when zooming in in the pdf, so it doesn't look very good. Any suggestions?