The Bass DI does indeed simulate a mic'd amplifier.
It's a pretty good unit, but don't expect to be blown away immediately. Recording a bass directly never sounds impressive until your listening back to the mix anyways...at least not in my opinion.
Some tips if you get this unit:
1) It doesn't put out enough juice. It works best to run it into a decent preamp...even something simple like the ART Tube MP works great. It's XLR output is balanced.
2) Keep a good battery in it at all times, or use phantom power. I use phantom power from my ART preamp which works great.
3) The presense and drive knobs are what will give your sound a "realistic" quality. Presense will give your sound some "air" and the drive knob will give it that overdriven tube sound (to a degree).
4) This unit works pretty will with regular guitars also. In fact, running a six string into the Bass DI produces a more realistic "tubey" sound than the POD.
Anyways, it's worth a hundred bucks for running bass direct. A HELL of a lot better than just plugging your bass into the mixer.
Slackmaster 2000