Since you have experience sailing catamarans, particularly smaller ones on the Great Lakes, I think that you are a few steps ahead of the game as far as knowing better what you will be comfortable with.
I'm a monohull sailor, and monohulls sail differently from multihulls. Storm tactics are different, for example. As a firm believer in experience (and developing the habits of good seamanship), I believe that with the right skipper and crew, just about any well-found and well-maintained boat is capable of crossing oceans. That doesn't mean that one would want to sail on some of the boats that have completed circumnavigations!
We had a friend who was an avid and extremely experienced multihull sailor. He built a 52-foot catamaran and took it across the South Pacific, two-handed with only his (inexperienced) wife as crew. To our eyes it was a huge boat, but he felt that for crossing oceans he needed an even bigger cat, which he subsequently built.
He did qualify his views with the comment that his crossing of the Pacific was done on a short budget and so he didn't wait for perfect weather to make his crossings and so encountered a bit more bad weather than slower, more cautious cruisers would encounter.
When we sailed to Easter Island, which meant sailing well south of the standard “milk run” South Pacific crossings, the first half of our crossing was a beam reach, a less than comfortable point of sail for days on end, but not intolerable. At the same time a catamaran who started the sail to Easter Island from the west coast of California or Mexico decided to give up the fight and changed course after several days and wound up sailing downwind to the Marquesas instead because the discomfort of the beam seas were intolerable to the wife. At the time I thought that she was simply too inexperienced and new to sailing to overcome the moderate discomfort of this point of sail.
Since our trip across the Pacific, we’ve sailed a friend’s catamaran on several delivery runs, and we now own a power catamaran. I think that the difference in motion between a monohull and a catamaran is significant and should be considered in one’s choice of a cruising boat. I personally don’t like the motion of multihull in strong winds and a beam sea, or worse, confused cross seas. Even in our light-ish Jeanneau monohull, our boat’s motion was not as bouncy as what we’ve experienced on the cats we’ve been on. However, I should admit that many people find the liveliness of our monohull, Watermelon, to be unacceptable, preferring the heavier, slower full-keel “cruising” boats.
As usual for me, that’s a long way around to the say that I see no reason why a catamaran of the size you are considering would be unsuitable for blue-water cruising, with only two people for crew. The caveat to that is, of course, “a seaworthy boat”, whatever the number of hulls.
Twenty years ago we met a fellow, Beaufort Beach, who sailed on his (very large) catamaran, Beach House. I can't remember if he circumnavigated on the boat, though I believe he crossed the Atlantic from US to Europe and back. He loved his boat.
There have been quite a number of other sailing cats that have circumnavigated (most notably, due to their blogs and rather insoucient attitude, Bumbuzzle). Another aspect of the Bumfuzzle blogs is How Not to Buy A Boat! One pays a surveyor for a good reason - to be sure that you are not buying a lemon.
And here are links to one instance of crew who ran into weather problems on a catamaran – the second link shows that it was the crew who had the problem, because the boat came through it fine. I do not mean to minimize the dangers and discomforts of a Tehuantepec’er, because it has brought many a boat to grief.