I don't have enough experience offshore (and none in any ocean) to offer an opinion objective enough to meet John's criteria - I'm also lying on my back on a sofa! - but here are my observations.
If ocean sailing is mainly off the wind, then surely pointing ability isn't a key factor, whereas ease of tracking is. Modern electronic autohelms might be pretty reliable, but they consume power (which windvane self-steering doesn't) and if they fail, or your supply does, then you've got a lot of human steering to do before you reach land, even more so if you're short-handed. In which case, I'd prefer a boat which tracks reliably, whether fin or long.
Long keelers tend to be narrower in the beam, so one's got less distance in which to fly through the cabin if things suddenly get hysterical.
As has been pointed out, ease of heaving-to and comfortable motion have to rank quite high, whether fin or long.
I can't see how any limitations of handling in astern would seriously effect an ocean-crossing yacht. Its not like you're stopping every night in a tidal sardine-packing factory.
I've got a small long-keeler - its what I've got, it handles okay in astern, is comfortable in a seaway, tracks easily, gives me more than enough space to be on my own or two up. It also fulfills my idea of the sort of boats I like, which is as much about personal romance as objective argument. If I ever change boats and moved away from long keels, then it'll probably be for a heavy long-fin.
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