As for catamarans sailing good COG to weather vs. monos - you should try actually sailing a Catana, Outremer, Switch, Atlantic or any of a multiple of other well-appointed comfortable cruising cats that will out-claw upwind almost any similar sized cruising mono you can name.
When you think of the necessity for going tight to weather in an offshore boat, do you forget about "blue-water" monos like BCC's, Hans Christians, Westsails, Pacific Seacrafts, Cabo Ricos, Whitby's, Southern Cross's, etc?
Almost all cruising catamarans will out sail what many consider to be "blue water boats" to weather. And I don't mean that to be that cruising catamarans are windward witches. I just meant to point out that many (most) "blue water" monos don't go to windward well at all.
Mark