Rudder/Post - The new Sabres use a Carbon Fiber rudder post (much lighter) whereas Catalina uses solid stainless. I am not sold on that yet for that purpose but it does shave off more weight on the sabre. I would be surprised if the old sabres use Carbon fiber posts. I also would be surprised if their old boats use foam coring.
Interior/Finishout - Sabre. I strongly prefer teak (which is what Catalina uses), but the Sabre finishout is superior. They put in more cabinetry and take up the available space much better than the Catalinas do. This has long been one of my frustrations/complaints about Catalinas is that they don't put in enough cabinetry. I actually spoke to Warren at Catalina about that this morning and it is all about cost. I guess they figure that the cost factor would be better having the customer do it after market versus them raising it across the board for all boats of a model. I proposed him having an option for a 'cruising package' instead which took up more of the available space. Who knows?
Layout inside - This is all personal preference folks. This is very subjective to the person. But I will tell you what I like and why and that will be very different for everyone. So there is no right or wrong answer here. I would not buy a live aboard boat without a separate shower in its own stall. The spray goes everywhere and makes a mess. Plus, it is apt for mold if you cannot easily get to every available spot. I also do not like any wood or teak in my shower. It looks pretty but is apt to mold and is a maintenance frustration (my dad's T42 has lots of teak in the shower and he is always having to air it out). Next personal preference - The V berth is the most comfortable place to sleep in... but the hardest to get out of. I like a large bed that I can roll out of. Why? I get up in the night to pee or she does. I get up at night to check the anchor. I come to bed late after reading. Etc, etc... but the bottom line is that I want a berth that I can get in/out of that does not disturb my partner. Plus, it is a LOT more comfortable not having you feet up against the other person. That is why I do not like the Sabre arrangements that I have seen. On my 400, I have a full size (nearly king size) bed. I wish I had more head room, but it meets all of our personal requirements. I also have a separate shower stall and LOTS of fiberglass. I think it is a much better live aboard set up.
Component and accessibility - This is a big plus of the Catalina... and I would assume the Sabre has a similar motto - make everything capable of being removed. When they build these boats, they lay all the furniture and wiring runs in them while the top is off. You will see this in the pics. They do this because it makes production a lot faster and a lot less expensive (BTW, just a side note, but did you know that Valiant does NOT do that... they run most of their stuff afterwards to assure it will all be accessible... interesting side note on why you pay more for a Valiant). Anyways, everything on your boat will break one day and you need to be able to access it and replace it. Catalina has long done that. I simply do not know about the Sabres, but I would assume they have done the same. Also, Catalina lays a lot of wiring and plumbing runs that are easy to follow and pull more wiring through. This is especially important on boats with liners because that accessibility under that liner is difficult. So having a tube to pull all your wiring through is a positive.