Catalina, Beneteau, or What ?
To begin with, I never said that I thought that Beneteau number series are ''poorly made''. I personally like the build quality on most of the Beneteau (including the ''number'' series) products more than I like the boats that come out of the other three of the big four boat builders, but I stand on my statement that the number series boats are just not as robustly constructed or as nicely detailed as the First series boat.
This is not about speed, it is about the whole range of details that are not all that hard to observe if you take the chance to compare a similar sized number series boat to a comparable First series boat.
To give some examples, on the First series boats, the bulkeads are tabbed in with pretty wide multi-layer tabbing. On the number series (like most value oriented boats built these days) the bulkheads are glued in. While modern glues are so tenacious that they will tear apart the plywood and the fiberglass before they let go, glued bulkheads have a very narrow contact area and so the loads get concentrated in this narrow glue line. The small load distribution are means that damage to the plywood or fiberglass is more likely, especially over time.
Similarly, the First series boats have a series of glassed in longitudinals as well as a partial glued in pan. The Number series counts solely on a glued in pan. Glassed in stringers do a better job of distributing the loads into the skin of the boat and allow a more careful set of connections. Structural pans provide a lot of strength and are widely used in the industry (even by companies like Island Packet) but in the end they tend to be heavier, harder to seamlessly repair and more likely to be separated from the hull due to fatigue, or in a grounding or collision. Even in comparing the width of the hull to deck flanges and the spacing of the two boats, the Firsts have a wider contact area and more frequent bolt spacing.
In terms of finishes and details, the Firsts just seem to have a few more niceties, especially when it comes to their deck layouts and sail handling gear, or grab rails and crash bars down below.
If you are saying that a number series boat has more room for its size, and you are determining size based on length, then I would agree with you that the number series boats are more roomy. BUT if you size a boat by its displacement, which I strongly believe tells you a lot more about the size and ease of handling and maintenance, then the First series boats seem to offer a little more useable space for their size.
The fact that these boats are used extensively in the charter trade really does not mean much to me. While charter boats clearly recieve far more abuse than most private yachts, they come out of charter completely chewed up and spit out.
Lastly, with regard to your mention of the article by Practical Sailor, I think that my comment in the first reply to this thread basically agrees with Practical Sailor, "To answer your original question, based on my own experience with both Beneteaus and Catalinas and a fairly large number of conversations with marine surveyors, I generally consider the design and build quality on the Beneteaus better than on the Catalinas but there is bound to be a large variation in opinion on that." I beleive that there is a place for boats like the Beneteau number series (or for the other value oriented boats for that matter). These boats offer a lot of room and reasonable performance for the dollar. If used as most people use a boat, weekending and short leg cruising where you are likely to be on the hook or at the dock at the end of the day, these boats offer a lot of boat and reasonable performance for the dollar. But it is a mistake to think that they are as robustly engineered or sail as well as they could.