I have to say, as ChrisTarman is mentioning, I have gotten the Martin bug and have never had one that had poor intonation. I will say these three points, only from my experience:
The 1950s-1960s Martins have something different about them than the decades prior. I think it's a thicker neck--they definitely (all of them, I've had a few) have a different feel than the 1920s-1940s Martins, and they do NOT sound as good. Deader, less chiming sound. I do not like 1950s and 1960s Martins. They are--as someone points out below--built differently. (Although I have never had one that had poor intonation, I can see how that might happen with 50s-60s Martins). I do not like and will never buy again one from 1950-1969. (I still own a 1964 O only bc that is the year I was born).
I have never had a Martin, earlier than 1950, that sounded poor in any way. All jangly (a Peter Forrest term), all ringing long and loud. They have a thin neck, and thin soundboards and really rock out. They are absolutely delish. I have never played one before buying it, and have yet to get burned on sound (I have had several from eBay with "no cracks" that did have cracks, though).
I have 3 Martins that were made since they restarted manufacture (2012 models) and they, too, are different than the vintage ones (pre-1950), with yet again thicker necks and denser woods (especially the cherry 3M), and while I do not find them offensive, and they are well intoned, I definitely do not find their sound to be anything close to the pre-1950 models. They are, and I have weighed them, heavier construction (by several ounces) than the early Martins, they feel heavy in the hand, and they do not ring out or have the sustain of the earlier Martins. Kiwayas fall into this category, too: excellent build, slightly weighty, perfect intonation, not particularly loud, "tight" sounding, and missing something that vintage pre-1950s Martins have.
So, all in all, Hodge, you know ukuleles; you have owned many great ukes. I would suggest to you to try a 1920 (earlier if you like wooden tuners...lol), 1930 or 1940 Martin, using Walsh as a buying guide, and I think you will be impressed. -- Steve
PS Sign up for Four String Farmhouse to learn more, Hodge. Many UU'ers on there, too (RyanMFT, GaryG, RFrogner, CTarman, UkuleleZaza, UkeBeare Terry, Gaspar, and on and on).
http://theunofficialmartinguitarforum.yuku.com/forums/8/t/The-Four-String-Farmhouse.html