Hmm, this is quite a vast question...
Basically, when recording bass I always use my SansAmp Bass Driver DI as part of the final tone - it's quite inexpensive, sounds killer, and is pretty much a no-brainer to configure (the manual is just a few pages). However, it may not provide enough control on midrange if you use it alone, so I don't record it directly. Instead, I use its "wet" main output for monitoring only and record the "dry" parallel output. Then, when I'm done with tracking, I reamp through the SansAmp, and also through an alternate amp or ampsim that provides better midrange control.
For your "alternate midrange source", if you or your bass player have a good amp, a suitable room and are experienced in miking it (or have enough time and patience) you can give it a try. Otherwise go for software amp simulation... I personally like the SVX plugin, it's basically an Ampeg software sim, but I wouldn't use it on its own: the typical Ampeg tone has a nice, full and rich midrange (which is precisely what the SansAmp lacks), but somewhat lacks of aggressiveness and low-end definition IMO. However, with a good overdrive pedal in front of it (the models included in the plugin aren't great for me, so I reamp through my good ol' DOD overdrive pedal instead) and when combined with the SansAmp, it sounds killer. But I'd gladly use my SVT-3 Pro instead of the SVX if I had a room, a mic and an 8x10 cab
This being said, I'm not sure I understood well what type of music you intend to record, as I hadn't even heard of "moshcore" before
But with an Ampeg (or SVX) + SansAmp combination, I guess you can obtain great results in many styles... Anyway, I think you'll need some overdrive or distortion pedal in front of your amp/ampsim to get the sound you want.