Sorry for the late reply. Life, and all that.
First thing I don't understand is why you threw in the Tartan 40 with the newer model boats? Did you mean a 4XXX/4100? I have not seen a 4000, but raced against a 4100. Nice boat, but do your homework first and go to this sailing site and ask them about Tartan: Anything Sailing Forum
We cannot discuss it on this forum.
As far as the Sabre vs Catalina, I will mention a few things then refer you to an indepth discussion I had about these on this page: Sabre 42- comments appreciated vs IP
I like Sabres. Great finishout. THere are some things about the 402 that I don't like for my use (cabin arrangement, water/diesel cap/a few other nitpicks). You will probably be able to review many of those on the link.
Like stated above, I relaly think the C400 MKII is the best of the Catalina line. I feel that those who categorize Catalinas negatively have probably not spent any time on that model. She is fast, sure footed, well finished out, and very comfortable. The cost will be a bit less than a comparable Sabre, but not considerably less. You will probably not find a lot of them for sale because the owners tend to hang on to them (especially with the new ones outrageously expensive... but so are the Sabres and Tartans). Another boat to consider that I have not had the privelege of sailing is the Catalina Morgan 445, which is like the bigger sister to the 400. But the cost of that boat would likely be more than either the Sabre or the Tartan. I would also look into an X.
I could say a bunch about the boat, but I will let you take a look at the links first.