...I still dont see any great "leap" from a say 550d to the 60d ?
Yeah, you're right. The pentaprism vs. pentamirror VF, ~40% faster frame rate, much better AF (9 crosses with a dual cross vs. only one cross), one stop faster max shutter speed, bigger battery for more than double the number of shots on a charge, better build with some weather sealing, better ergonomics (top LCD, etc.), all that's irrelevant.
I understand there are many other important components to a body......I still dont see any great "leap"
Since you understand there are other important components to a body beside the sensor, and you still don't see a difference between the 550D and the 60D, what 'leap' are you expecting? It's one level up...you expect Ferrari power and handling if you get the Accord instead of the Civic?
Oh, I get it...you must one of those people who expects a 1-series body for $1000. That Entitlement T-shirt must look even better than the DxOMark T-shirt!
Sorry, but I really don't see the point of your post.