In reply to Shapeshifter:
Hi there I did it quite a few years ago, I didn't take any extra gear just used the bolts, it gets 1 star in the Cambon guide which means that it is fully bolted, I have never taken extra gear on a 1 star route's and always been fine, 2 stars is normally ok if a little run out in places or just older bolts.
May is very early for the Cerces, I live just down the road and don't start thinking of climbing there till July and August, it should be clear of snow, but it could be quite cold especially till the sun comes over.
Another option or back up plan could be a route on the Tete D'Aval some great climbing and its south facing and May can be a good time as not to hot like summer?
Cheers Rob