I tried a 120/70 on my ninja 300 (race bike), not exactly the same bike but something to compare to.
Pro's: it increased the height of the front end (only by a couple of mm's but I was having corner clearance issues) and there are more options for soft rubber (there are a lot more options available now though)
Cons: the edge of the tyre was very vague, you couldn't really feel the front end "push" and it didn't inspire confidence. I tried it aiming for more front edge grip as I was riding to the edge (and beyond on occasion) of the front but my lap times, corner speed or trail braking didn't improve.
I have a mate that doesn't get to the edge of his front tyre and he couldn't really tell the difference