One thing to keep in mind about the silver jubilee combos is that I am pretty sure they don't have a choke, so they do sound different than the heads. This is what I remember reading anyway.
I used to own and Engl Fireball 60 and currently own a marshall 2553 silver jubilee, here is how I would stack them up:
Clean: Neither is great. Not much of a clean on the jubilee with humbuckers, but pretty nice clean with single coil pickups. The Fireball sounded very clean, but flat and compressed, almost SS sounding.
Mid gain: I don't really like the rhythm clip that much, but turning down the distortion does give a pretty good midgain sound. The fireball didn't really have a midgain.
Distortion: The Jubilee has a very classic 80's hard rock distortion. With an EQ in the loop it can get into more modern territory, but never really nails it. It also can be buzzy if the amp is played too low. This was the sound I bought the jubilee to get. The fireball has a great distortion too, much more metal. I couldn't really get that 80's hard rock sound from it, but it excelled at all out metal.
Hope that helps a bit.