Rednet has the advantage that it doesn't connect to a variety of basic blocks like stone and grass, so it won't energize them like redstone or red alloy wire will which reduces unnecessary block updates (although insulated wire has the same advantage). Rednet also has the disadvantage that it doesn't connect to a variety of basic blocks like stone and grass, so it won't energize them like redstone or red alloy wire will, therefore you can't have a lever on a stone wall that activates a wire on the other side. In other words, with Redpower, you have the choice of whether you connect to stone or not. With Rednet, you don't. You do get multicolour signals for free, which needs bundled cable in Redpower. Not sure about "chunk updates" as I have no idea what they are.
I don't know if you can attach an Immibis Microblock stone cover to a Rednet cable and then put a lever on the cover. I suspect not, but the Rednet cable might be smart enough to spawn a connector on a side when a microblock cover is attached to it. It only generates a connector on sides that have blocks that are "redstone aware". Maybe an Immibis cover counts, or... ooh, maybe it detects the lever on the other side of the cover as a conenctable block. Actually, that's probably it, it should work.
Rednet cables are probably simpler to render than complex wiring that goes up and down walls and round corners connecting to itself.
