Thanks all. Never considered the porus nature of spinnaker cloth before. Looking into new one.
Yes the Tanzer is rated better in a breeze. The Niagara is better upwind. Interestingly the I measurement on both boats is the same so I would think that even though the Tanzer is masthead its shorter mast means the chutes on both boats should be same size and the main on the Niagara much larger.