I'd love to have an extra option to choose between letting the dry signal come through mixed with the Green Scream.
So u have an extra option to have 50% clean tone and 50% tubescream driven, which would be great for some amps.
Some amps like the 6505 or most ENGL amps don't really need a tubescreamer, but could use just a little bit more tightness(where a tubescreamer comes in handy)
When u choose to use a tubescreamer, u'll always end up losing some body, having the choice of how much the tube screamer get mixed in would be awesome.