I'm going through the same exercise as well. From what I've read, all are fine cloths that will suit you well given your requirements. I don't have my materials here but I think that Kappa uses Challenge too. I was seriously considering the same short list of sailmakers but placed an order yesterday with Bacon's in Annapolis for other reasons.
My only concern with Kappa is that they use a very odd mitre panels (oriented with the leech and foot) for their headsail and use 2 cloth weights. I'd go with a straight crosscut and stay away from the mitre. KISS.
Sabre 38 "Victoria"