Sorry to add so late to the discussion, but at what point do "modules" or modularity become an entirely new robot?
I'm re-designing a beetle right now and I realized that I could make the weapon system modular from an overhead bar to a vertical drum, but this would pretty vastly change the appearance of the bot and about 2/5's of it by weight. The majority of the chassis, drive system and armor would be the same and the entire electrical system would remain exactly the same. I'm mostly asking because of how different the two configurations look in CAD, it almost appears to be an entirely new bot even though the slim majority of the components are the same. If I had a modular drive system as well, I would essentially have two complete bots I could mix and match parts to.
The closest practical example I can think of is Nyx at 2015 Motorama who had a bolt on weapon system that used exclusively the ax attachment after the lifter burnt out. Mike did a great job in making the system explicitly modular; Nyx would work as a box bot without any weapon at all. However, if for some reason he made his 4wd system modular with treads or a shuffle system, would that still be bueno? That is to say, if Nyx went in as a wheeled ax bot on one fight and a shuffle lifter on another, would it be considered the same robot?
I know the rules and the spirit have been pretty well spelled out in previous posts, but I just want to make sure no one'll get mad if I show up to a fight against a Trilobite kit with him expecting a horizontal spinner and getting a face-full of drum instead.