Thanks, everyone.
The Markbass seems to be made for my Sterlings. Something about the mid voicing of the Sterling and the Markbass really shines and cuts through. It's really uncanny. My Bongo, on the otherhand seems to like the Epifani cabs more to my ears.
Edit: Sterling_Bass - I saw your question on the MB Megathread. The MB cabs get mixed reviews here. I can understand why - when I play them solo, I'm sort of like, OK, that's cool, but it doesn't seem to knock my socks off. But when I play it in a gigging situation, the MB cabs rock. I think that's the same with the Sterling voicing. A lot of people like the Stingray more cause it has a little more bottom and a more scooped sound, but I like the way a Sterling cuts through with more mid voicing.
I think it's also like how the best tone that cuts through a mix is a mid/low-mid tone that, when listened to solo, can sound sort of honky.