I am a couple Kg lighter, and on a rented freewave 86 it was not a problem, though it was on a long period swell and no chop. I have tried it once on a 80 litre wave cult, and could not make it happen. If your uphualling at that 'advanced' level it is no longer just that it floats anymore, it is also how stable it is, particulcarly for and aft at complete rest, which it won't be!

For me I would say 95 litres is the limit if you need to depend on it with no stress, and about 85 litres, if you situtation can cope with a few mistarts and you are prepared to practise it a bit, below that I would not want to be depending on it to get me home...