The university where I teach bought 990's for a bunch of the faculty to keep in their studios to record lessons with students. I was prepared to hate mine based on what I read here on this forum. What I have since discovered is that most of the people who are dissing them don't have any direct experience with them or are just turning up thier noses at anything chinese. For what it's worth, I think the one I happened to end up with is a fine mic for what I need at the office: it's got a good strong signal, a pretty wide pattern, and is a hell of a lot more open and detailed than I would have expected for $50. Is it the be-all and end-all of mics? Nope. Is it as good as a $2000 mic? Not for most applications. But it doesn't suck by a long shot, and for $50, waddaya want?
I also have a B1 at home, and it's a nice mic for what it does as well. I like it for upright jazz bass, especially when you are able to isolate the signal from bleedthrough. Again, don't listen to the naysayers unless they've tried the actual model of which they speak. Both are decent mics for the money. And considering the money ain't much (especially for the MXL), you don't stand to lose too much if you try it. If you're just starting out, you'll have plenty to learn about mic placement, room treatment, signal strength, etc. before you reach the "headroom" of these mics - in other words, they'll make good learning tools, and when we're just starting out, most of us have plenty to learn about what we're doing before we have to worry about upgrading our tools. A lot of the GAS you hear about from beginners is often just people wishing/hoping that some new piece of gear will compensate for their (our) lack of experience with recording technique. At this price point, order either mic, and get recording. Good luck!