Another +1 for the Trace 1153! I regularly gigged a late-90's (Pre-Gibson) model for several years and loved it... it never let me down once! That Celestion driver could handle a lot more power than its specs would suggest, and it sounded great for pretty much every style of music I play. It turned out to be a great recording cab too, especially with a Bassman valve head!
Having owned and gigged my Compact for a while now, I think that overall it's a vast improvement on the Trace in almost every area. Loads more power handling, loads more bottom end, far more balanced tone from top to bottom, better tone at loud gigging volume, much much lighter, smaller and much easier to carry/transport...
However, on the downside I must say that although the Compact is built very solidly where it matters, it's let down a bit by the finish, compared to other high-end cabs that I've owned. I ran the Trace for a decade and it still looked great when I eventually sold it, thanks to the tough carpet finish and metal corners. I have my doubts that the Compact will age as gracefully. The painted-on finish is already displaying chips and marks (despite me being very careful with my gear!), and I'm just not a fan of the plastic corners that Alex is using- they are cheap compared to the rest of the components used, and break easily (two of mine have split, although Alex has sent me replacements through).
Sorry, this has accidentally turned into a review! Back on topic now... I've briefly owned a pair of Aggie GS112's, and must say that I greatly prefer the sound of a single Compact to a [u]pair[/u] of these!