are the new boats block location further forward than original boats? they seem rather far forward from most classes (say m24, j80) that have them really far back? how does this effect performance and the spinnaker design?
The blocks are located further forward. The turning blocks aft would have a big effect on how you design your sail. The leech would be far more open with a kite designed for further forward blocks. You would have big trouble on any sort of a reach or sailing hotter angles. You would however be able to sail very deep and slooww. Most boats with blocks a long way aft have twings (pulls the lead forward) installed for non OD reaching legs.
The older boat's had turning blocks that were pretty far aft if memory serves. I raced on 33 in Arizona. It had the blocks in the back of the boat and it was a real PITA. Your correct, the turing blocks are much farther forward.. you'll find the spinnaker sheets stay out of your way, spinnakers have a bit more area on top, shorter foot and gybe much easier.
Also don't forget in the new block positions the blocks are further outboard. Outboard equals better. The further aft you were to move themthe more inboard they would be.