I am using Audacity to transfer my reel to reel and cassette tapes to my computer. It takes a little learning, but, so far, I love it.
...so some EQ might be necessary, but you could spend a lot more and get a lot less.
Beyerdynamic MC903: This has a reputation for being the poor feller’s KM84, though it seems a little warmer, less bright than the Neumann KM84.
Yeah, you can use Audacity to do a lot of things. But once you use a program actually designed for musicians, and not computer programmers (and this is coming from a computer guy), you'll never want to touch that thing again. It's horribly obtuse to get anything done that you'd actually want when just trying to jam, and get a recording of it.
As for mics with less than linear response, as long as the noise floor is low enough, you can totally change the character with an EQ. So don't worry about "bright" or "dull" in reviews, all you need to do it throw a parametric EQ on insert effect chain, and voila (not viola).