GlennR,
My first "BIG" boat was a Nordhavn 55. It is rated to cross oceans, and could. However, in the almost four years I had it I did not cross any oceans, although I did go as far as 400 miles across an ocean, from Nantucket to Bermuda, and spent quite a bit of time 200 or so miles offshore.
The rating was most important in that I always felt incredibly safe on the Nordhavn. My current boat is a North Pacific 49 and it is a coastal cruiser. So, I "have to" stay within a couple of hundred miles of shore (my insurance carrier says they don't really care). That means that I don't cross the Atlantic or the Pacific.
But I CAN go, should I wish to, from the north of Canada to the southern tip of South America (or, of course, through the Panama Canal, which I actually have done), then up the entire coast of the continental United States, past Canada and to Alaska.
That should cover it for me.
Now, would I feel as safe in the North Pacific as I did in the Nordhavn. I don't know yet, but probably not. So, what would be the practical consequences of not feeling as safe? Well, I would stop more often along the route for weather certainly. I would have to spend more time in ports in some of the most interesting places in the world. And, I would need to have the time to do so.
Doesn't sound too bad.
I really planned to cross the Atlantic. I was going to do it after 3 years of getting to know the boat. In the third year my wife had an allergic reaction (not just a normal, localized reaction) to some bugs in the Caribbean, and that was the end of boating for a few years.
My Nordhavn was bought by a "retiring" fishing fleet captain/owner who did indeed want to see the world with his wife before they were both too old to do so. I never got to meet the man, my broker handled everything, and I don't know just how things turned out, but I hope he had, or is having, a great time.
Very few people who think they will cross oceans actually do so. I still dream about having my North Pacific in the Med for a couple of seasons, but will have it taken there on a yacht transport, while my wife and I fly in.
Enjoy your time.