I'd say Chuckles is right....define "OffShore" first.
I have an '83 Newport 27-S MKII, and have been in email contact with George Cuthbertson, one of the "C"'s in C&C, who designed the Newport 27, asking that exact question about my 27, and his words were "I would not hesitate to take that model offshore."
Now, of course, he's talking about the design itself, not necessarily what a builder DID with his design. So if Capital Yachts used lighter hardware, etc., than he intended, that would temper George's recommendation.
But I know mine is solid as a rock, solid, non-cored hull, good hardware....and I've been caught in a serious blow or two and she handled them without a whimper or a threat....so I've felt completely safe in my "little" 27.
But, again....define "offshore". One old timer who was looking at mine while both of ours were up on the hard, said he would not hesitate to take mine to Bermuda...and he had some monster double-masted thing that was at least 40-some feet...and said he sails there all the time...
The real issue is weather....not just stereotyping the size of the boat....if you're caught out in serious weather, even in something much bigger than a 27 or a 30, size isn't going to save you.
IF you've planned the passage, and have clear weather, the Newport 30 will get you there fine.