I'd say if you're going to change the variator, change everything else as well. ALL tensioners (cambelt & balance belt) and BOTH belts.
You never know what was done to the car before, even if you have service history. Not all "mechanics" are mechanics if you know what I mean.
When I got my ti, the previous owner swore he had got the belt& tensioners done. I asked him for the shops receipt but he "couldn't find it", so he sent me to the shop. The mechanic there told me the same thing, but he didn't say which tensioner/s neither did he mention the balance belt.
I still ended up buying, but there was not a single day that I drove the car without thinking in the back of my head "will a tensioner or belt go today?" It was VERY stressfull.
You will sleep better I can asure you
As far as i've seen, a repair for a belt snap in europe costs, in most instances more than the cars' value. If it happens you will never forgive yourself for not spending the extra cash.
I've re-used cambelts on my 8v 33 as they had been recently replaced, (had to take it apart for an engine rebuild) but this was a different animal and the belts are no where nearly as stressed as compared to a 16V with variable timing.