Been using Markbass CMP112 combo for 2 years now for all my Gospel Shows and now looking to add a NY112 cab to it. I had try all different cabs with my Markbass F1 head and it now using it with two GK 112 cabs for my church rig.
It sometime take a while to find the right match for what you're looking for sound wise. Keep trying out those amps at GC until your ears say that the one. I try to go to where I can hear a amp live; like a club or out door show.
I used a Little Mark II with a 15" cab (forgot the brand) at a local jam last week and I didn't like that tone combination at all. Mostly a boomy sound with no clarity. So the cab selection is important with most amps.
PS: The cool thing here in the Bay area are all the jams where you could test all kinds of bass gear in 'live' situations.