I approve.
The new "from one come many" feature is new, but it fits with the Modrons' themes of being a collective, non-autonomous unit. Plus, the
literal idea of Primus as a distributed individual fits well with previous editions'
figurative suggestion, and gives combat a little variety.
I also think it's hilarious that quadrones basically chuck minions at people.
I'm also kind of fond of all the "force" damage and movement abilities getting tossed around. It's an evocative power type for them, and makes the "march" seem very...resolute.
The bit about them closing portals isn't something I remember, but, again, I think it fits with the themes. If portals are causing chaos and unpredictability, the Modrons are going to want to close it! It's a good way to introduce modrons to any world, but enough of a throwaway to ignore if that's not your style.
I am OK with the modrons being separated into basically 4 different monster types. I would've liked some more variety, but I grok that
Dungeon articles need to be short, and the way they made the distinction has value (into monodrone minions, duodrone and quadrone regulars, and heirarch elites) and leaves plenty of room to add more.
Only thing I need now is a modron outcaste's racial rules...

(I also prefer "modron outcaste" to "rogue modron," since 3e and 4e have rogue as a class, but that's a nitpick, and the former name is something I invented, so I couldn't expect them to use it)
I like it, it is good, and I am *absolutely* using these creatures.
PS:
A Little Bit Of Context For The Article