All depends on how much you like changing gear! If you catch a 16v off the cam when you put your foot down you won't go anywhere for a while unless you drop a few cogs. With the 8v you can accellerate quite well in 5th at 30mph. That said, the 16v gearbox can take the extra abuse needed to get the most out of it. Both are great although I am starting to see the limitations of my comparatively "stock" 8v.
Variable valve timing would be handy....