New designs are always faster, it works like this.....

Say you have a three year old "Design X", you've raced it pretty hard and done well. Then you test sail a brand new "Design Y" and discover it is stiffer, faster and more responsive than your current boat, therefor it must be better so you sell your boat and buy the new one.

The truth is 90% of the 2% difference is that you're comparing 3 year old gear with brand new stuff. Test sail a brand new "Design X" (identical to your current boat) and you'll probably find the same difference.

One thing most F18 sailors will tell you is all the boats (including the older designs) can have their day, More than anything else the new hobie is a marketing and fashion exercise because after 12 years the Tiger is falling out of fashion.