For a combo, you don't want to use a Greenback. It won't last long. It breaks up way too quickly too.
I used a Mojotone BV30H (Heritage 30 clone) in my DC-3 and it was a dramatic improvement over the Vintage 30.
It was very warm, yet retained that British sound like the Vintage 30, but with tons of added bass and less mids.
I tried the following speakers and decided on the 30H because it was the warmest sounding and did not muffle the amp in any way.
Vintage 30: Sounded like a swarm of bees, very buzzy and boxy sounding.
Weber Thames: Great for cleans, lots of sparkle, but not enough depth for distorted tones.
C-90: Great for distorted tones, but seemed to muffle the cleans (which is weird since I love this speaker in my LSS).
Mojotone Greyhound: OK, but not in this amp, it sounds much better in a Fender amp that is bass heavy.
BV30H: Warm, fat, and pleasant to listen too. Not too shrill, not to chubby, just right.
The Vintage 30 used to be my favorite speaker when I played metal, but now I need speakers that have more depth to them. The V30's seem too harsh now.