Generally, i do agree with that philosophy. My hangups with this particular scenario is 1) price gap (100 @ $300, vs 200+cab @ $800) and 2) this is comparing one 200w, 2- speaker rig to another. Its not like im looking at a 500w head with room to grow.
I do see the pros of the 200, a 15w speaker and a 140w one- piece amp when i want it. Also, i could just skip the ext cab an chain the 200 to my 100!
Again, the 100 is enough for the vast majority of my gigs . Just wanted backup plan/alternative for those special occasions. I wouldn't think of dragging out the 2 rumbles and chain them if it was for every gig.