Just sayin', watch the assumptions.
OK, so I made a few assumptions. To whit:
1. We won't ever be stuffing our bows at 15kts while anyone is on deck. Seriously, do you think people cruise this way?
2. I won't be on our hardtop, or even our cabin top in serious weather. Why do you think someone will climb onto the hardtop in inclement weather? What reasonable person even rigs jacklines on their hardtop? If for whatever reason going up there was necessary, then the procedure would be a specific one, with a specific plan, and not rely on a general jackline.
3. 7/64" dyneema may be a bit light, but even 1/4" will not roll under foot. Still a viable alternative.
I disagree that a person taking a prat fall on a wide deck, or having one foot slip, or simply jerking quickly aside a few inches, considerably exceeds a dead fall of 6' coming short on a tether. This is probably easily shown through simple physics, but most people's experience is sufficient. I won't do the math, since I'm not the one questioning it. BTW, nobody is running to the foredeck. At least not anymore on a catamaran than a monohull, and nobody will be doing it for 12' on a catamaran, since the tether is 6'.
I'm with JeffH in thinking that stretch works against one in this case. As for end fittings, of course they need to be matched with the expected load. Otherwise, it is like cautioning against connecting anchor to chain with shoelaces - pretty much a waste of breath.
But what about dyneema webbing? Doesn't seem too expensive, won't roll underfoot, good UV and chafe resistance, and stronger than polyester.