Judging by your Nom d' board, your goal is distance 'bluewater voyaging'. If that is a reasonable assumption, then this is a really poor choice. I know these boats pretty well, and would suggest that in no way would these be a good choice as an offshore cruiser. It was not the use for which they were designed and this design has a number of design items which would make them a very poor choice for offshore use.
In a broad general sense, ideally, when you talk about a boat for offshore use, you want a boat which is robustly constructed, which has a comparatively comfortable motion, and which also has comparatively small deck openings. You want a boat that is easy to move about on during rough going, which has sturdy interior appointments, lots of handholds and which has sturdy, securable storage areas. Offshore, you want the steering station and cockpit located where it minimizes motion in order to minimize wear and tear on the crew. And in the kinds of large waves encountered offshore, you want a boat with a high stability, and low vertical center of gravity.
In other words, if you are planning on going offshore , then you want something that is the anti-thesis of this boat.
To address the discussion above, by the time that these boats were built, Columbia was in financial trouble, they were cheapening the build quality of their boats hoping to remain competative in the marketplace. (I see that SoulJour deleted the reference to the second oil embargo but) To keep the history even slightly accurate, In January of 1973, during the Nixon Administration, the stock market had crashed and pretty much all of the major US boat builders were hurting. OPEC had found its legs and 1973 was the heart of the first oil crisis, the one that impacted the formulation of polyester resin and which created a market for power boats with sails such as the Columbia 45.
It was during this period that there was a near marine industry wide, or at least in the value oriented portion of the marine industry, reduction in build quality and Columbia (think of them as the Hunter of the day) was at the forefront of this corner cutting. The basic hull form of this boat was adapted from an earlier design, but the hull lay-up schedule (thickness and choice of materials) was lightened greatly. (BTW 1" is a very thin hull thickness for a boat of this size and weight) This was before the period when material handling techniques improved, and before internal framing became the norm. What this means is a boat that which really flexes noticably in a seaway and that kind of flexure will weaken fiberglass greatly over a perid of time. (The one that I knew flexed so much that you could not close door to the head on a starboard tack.)
The hull to deck joint on these boats was especially vulnerable damage to failure over time. This boat has the classic hatbox style joint, and this type of joint was a notoriously poor choice. There was an earlier thread discussing one of these boats (not the motorsailor version), which was being restored. The owner was trying to figure out how to repair
this type of deck joint once it failed as it had on his.
As the OP already acknowledged the large openings make this boat quite vulnerable in seaway, and if your intended use meant offshore passagemaking, then the large openings should be glassed shut, the cabin sides reinforced and smaller, heavier duty portlights installed.
Numbers aside, there is always a discussion about what makes a boat which can be taken offshore vs one that is ideal or even safe to take offshore. This is a classic case where the numbers are grossly misleading. These boats were real rollers. This is espcially true of the shoal draft versions with their deep canoe bodies, round hull sections, and low density iron ballasted fins. This model were also prone to more pitching in a chop than a more moderate model and their full bows threw a lot of water and were particular uncomfortable coliding with waves, exspecially for a boat this big. The deck layout with its high steering station, amplified this uncomfortable motion making moving about ,or even simply sitting, more tiring on the crew and more likely to induce seasickness (See the discussion on the Sinking of Rule 62 since the discussion of crew comfort applies in spades in this case).
If you are taking a boat offshore, the interior layout and details should meet a certain minimal requirement in terms of seaberths, handholds, footholds, proper seacocks and plumbing layout, securable storage, ground tackle
storage and so on. While individual owners may have upgraded any indvidual version of this boat, as they left the factory, there was no attempt to produce an offshore suitable layout.
Although this is a side issue, it is silly to say that the Columbia 45 is only .3 knots slower than a Beneteau. Whatever vitues and liabilities may come with either design, Under PHRF the Beneteau 44.7 rates 143 seconds a mile faster (31 vs 174). In real life that translates to an enormous speed difference, especially in lighter or heavier wind speed ranges. On a heavy air reach, the Beneteau can cover the same difference in half the time, and in lighter air the Beneteau can sail at close to hull speed when the Columbia is stuck motoring. But if offshore voyaging is your goal, I would not recommend a 44.7 either.
In the end the Columbia 45 motorsailors boats make great comparatively cheap live-aboards. They are okay in protected waters as long as their is a breeze. There are lots of great, inexpensive boats that can be taken offshore, and there are even more mediocre boats capable of making occasional offshore passages, but this design fits in neither category. So while SoulJour may be right that this is a good boat to sail into Vahalla, its a poor choice to sail offshore.