I'm not mixing anything up. I'm a labor economist and this is a known thing. For comparable job descriptions, the Feds pay more and require less. What is true is that industry will often pay more for the same profession, but they're different jobs and are generally much more demanding.

Laying off unproductive people does not tank an economy. That makes no sense and is just more Keynesian nonsense. I think there are more than four million federal workers, but they don't all get sent home during shutdowns, as you said. I don't know what the ratio is of "essential" and "non-essential" workers, though. Three million is probably about right. I was under the impression that the essential workers still got paid, but I certainly may be wrong about that.

Why bring up state and local? They don't shutdown when the feds do.

The last point is probably true, but I'm not a Republican, so I don't care. I get why that factors in to what's likely to happen, though. If they can make a permanent (or long-lasting) dent in the bureaucracy, I want them to take the opportunity. No other plan that I've heard strikes me as remotely plausible (and you didn't really contend with that).