Hmm. What if you want the first layer of speaker colouration (your cab) and the second layer (the PA) is reasonably flat and accurate?
My amp and cab is a big part of my sound, especially when using overdrive/fuzz and you need that natural top end rolloff. If I had the choice I would go for a mic every time. Needs to be a decent uncoloured mic that captures the low end though, the ones that get talked about most on bass forums are the Heil PR40, Shure SM7, Electrovoice RE20, and the Sennheiser MD421 (with the latter being the cheapest and what I would probably go for). Best to buy your own mic and stand and bring it with you rather on relying on what the sound man might have lying around, you don't really want to have to use a kick mic or one that robs your low end. If you only have an SM57 to hand, then blending that with a lowpassed DI is a good solution.
If you like a clear accurate representation of your bass and don't use distortion, then DI all the way!