A couple of things. I rode
out Irene on my boat in Mass. on a mooring in a relatively well sheltered spot. Probably had some 60 knot
gusts max, but most was a lot less. I've been through a lot worse just at anchor. But, I have been through this hurricane drill many times on a mooring and I always lengthen my painters, double them up, spread the loads out with every cleat I've got up there, use plenty of heavy chafing gear, and try to set one or two anchors out to back up the mooring. Most moorings depend on weight and are not very efficient in terms of holding power. After Hurricanes Bob, Carol, and Irene I saw boats on the beach still attached to their moorings sitting right next to them on the beach. In particular, the popular mushroom tends to not do much good in a hurricane. The trick is to somehow set and tend the extra anchor rodes so they don't tangle with your mooring and or the underwater appendages on your boat. This is exacerbated by the fact the winds will be clocking or backing around quite a bit as the storm goes by. At my mooring this was complicated by a strong current
in the river making the boat go up and over the mooring ball in the lulls. I have yet to figure out the best arrangement of anchors and moorings for my current location, but basically the more the merrier. Sure, you'll have a mess to sort out after the storm, but that is better than the mess you'll have to sort out if your boat drags its mooring. Also, Dyneema
may be great, but regular old nylon protected by heavy chafing gear has never let me down. Generally, if you use the right diameter you won't be anywhere near the strength limit on the nylon, so if you can control the chafe you will be OK.