Tabbed Bulkheads - Sabres, hands down (at least I think they are tabbed). Catalina does not tab (glass the bulkheads to the hull/deck). However, I am unaware of a failure of a large Catalinas bulkhead. Just so you know (on the larger boats), Catalina glasses in a 'lip' and mechanically fastens their bulkheads with screws. I guess you could come back and glass them in, but again, I am unaware of a failure of a bulkhead on a large boat.
Sugar Scoop/Step Transom - This is a huge one for me. I would almost put it in the deal breaker. As a live aboard/cruisers, we are ALWAYS on the tender. We are always getting on/off. We are always swimming off the back. My dad has a canoe stern (Tayana Vancouver 42) and many other boats have swept back/standard sterns and I HATE getting on/off those boats. And I can only assume getting someone unconscious on board one of those boats in a sea would be a nightmare if not very difficult (and without some type of winching, impossible for many people). Not to mention, I personally feel that davits and/or an arch is a must for a cruiser and it has always looked awkward to me for the swept back or other boats without a sugar scoop putting them on. It totally screws up the lines. I believe the 426 offers a step transom which is at least some improvement, but many of their other boats (including an option on the 426 is I am not mistaken) do not have it at all. You are going to hate taking the dog to shore, having guests over, (getting the kids on for me), etc with that transom. I do. I have experience with both and would not trade the sugar scoop.
I am sure I will come up with a lot more things to discuss about the two boats. In the end, I believe Sabre makes a better boat. There are things they do that you simply cannot replace (hull material/mfg process - which is not necessarily a positive for me but makes a better performing boat), and there are things Sabre does which make it a better boat which can be changed (access through the liner on the Catalinas, add more cabinetry on the Catalinas, SS Portlights with Dogs, Dorades, etc). There are also things about the Catalina which make it a better choice for us that you cannot change on the Sabre - the sleeping arrangement, totally separated and enclosed shower stall, Sugar scoop stern. But I think Catalina (or Bene or Jeauneneau) has gotten an unfair reputation as a coastal cruiser and cheap boat. I wonder how many Sabres have crossed the Atlantic compared to Beneteaus? How many Sabres have circum'd compared to Benes? An interesting thought.
So that is why I have said that Sabres are, to me, an expensive Catalina. Their build quality and much of their hardware is better. Their hull manufacturing is potentially a better process (I have my concerns). It should be a faster boat. But there are many things they do which make their boats a more expensive boat which you can also do on a production boat. And depending on where you are going to take the boat, I am not convinced that the things which Sabre does to make their boat a 'better' boat will be a big positive.
These are my opinions and I welcome any criticism.