Just got the issue today in the mail, but just from a very brief look in the last five minutes or so, I'm really liking where you went with this Ken. The bit regarding the corrupt secundus, I really like that playing up on the idea of lingering Tenebrous corruption in the ranks, and it damn near mirrors an idea I'd written up in a speculative little piece regarding an evil/corrupt secundus. Thinking more on it, I have the sneaky notion that you might have dropped the idea before as something on your mind, maybe a few years ago, when we were talking about the Modrons. Very cool 
My only real quibble is perhaps the bit about Bytopia (intended to be Ysgard or Arborea?), and the use of constructs as the modrons type (They only make sense to me as outsiders, though perhaps we can make a rationalization and say that the animating energy itself could be itself considered an outsider and the modrons might only be the shells that Law/Mechanus/Primus itself just manifests through.)
More comments later when I read more in depth.
Artwork for the article:
Julie Dillon is fast becoming one of my favorite artists. She did the artwork for my demiplane article in 353, and now your Modron article. Seriously seriously captures the atmosphere of these guys.
Aw crappit! Don't tell me I blew it on getting the alignment of the planes right! that's what I get for going from memory. I was mainly going for a good-aligned plane with a lot of residents that seemed very peaceful and easily slaughtered. When I think "very peaceful and easily slaughtered", gnomes often pop up at the top of the list. Hmm... how to retcon THAT one?!
As for the Construct type, I originally proposed having them all be Living Constructs rather than standard ones (since we have that with Inevitables already), but they nixed that and wanted them to be full constructs. I snuck in the Living Constructs for the exiled modrons, however.
And I've discussed this before, but, personally, I can go either way. Yes, they do make the most sense in the pattern of the planes to be outsiders like the celestials, fiends, and slaad. But on the other hand, I really like the balance that is struck by having the Lawful "exemplar race" breaking the pattern. It's sort of a deeper balance and structure than a superficial "they are all outsiders". Also, I like your concept that the animating force is outsider, but the shell that interacts with the world is construct. (Maybe the ancient modrons - depicted in 1e - were outsiders, but after really bad confrontations with non-modrons made a deal with inevitables to alter their forms... just take the anamoly in the rules, and make an interesting plot hook out of it).
*shrug* But I have no real strong feelings either way. At the end of the day, Paizo wanted constructs, so that's what I wrote.
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