I disagree with this comment.....

I believe that in challenging conditions such as strong winds or gusty conditions a spinnaker boat can be more vunerable than a non spinnaker boat as with a 2 man boat Vs 1 man boat.

This is because of the greater risk off losing ground due to mistakes during manovers on a boat with more crew or a more complicated boat such as one with a spinnaker.

It is more so the case with short course races where boats have to perform more manouvers in a shorter period of time. Spin boats can blow a drop or set. Crewed boats with the crew working together for the perfect tack, gybe or mark rounding have more off a chance to make a mistake than a one man boat that dose not have to co-ordinate with a crew.

I have seen many top A Class sailors on the heals of a Tornado in short course racing. Whilst the T makes the ground in a straight line the A Class can make it up on an efficent mark rounding.

On the other end of the scale, over a larger course, a Spinnaker boat can stretch it's legs with the kite up and can stay in pressure moving down the course longer.

Just my thoughts.