Shorter tiller extensions tend to get trapped more in life jackets (pfd) and tee shirts etc. There is nothing worse than going into either a tack or gybe to find your tiller extension poking through an item of clothing. So the longer it is the less likelihood of this happening. I would agree with everyone else regarding Gybing, it's all about being confident, the faster the boat is going the easier it will Gybe. Always avoid gybing when the boat is slowing down. One technique I have adopted recently is to pass the tiller extension around the back of the mainsheet (kneeling down) and resting it on the leeward hull, now I start to pull the tiller to initiate the gybe. Once the boat starts turning I start to twist my body round, swaping mainsheet hands to face forward (sitting down) and pick up the tiller with my free hand.
P.S. Great choice of boat, a couple of dozen capsizes and you'll become a true F16 Sailor.