I have a SP B3 and an MXL 604 and have tried many shootouts on guitar. You really need a mic with a flat (not hyped in the highs) frequency response.
I think the B3 sounds downright awful on guitar - scooped mids with highs that are too harsh and bright (and a little distorted). The more I try it the worse it sounds to me on guitar, although I like it on female and child vocals. I would highly recommend the MXL 604 over the B3 for the guitar and drums, if those were your two choices. If you wanted a large multipattern budget condenser, I would recommend the CAD M179 over the B3, especially for the drums.
I have always gotten better sound from the SDCs than LDCs for guitar and drums - SDCs capture the faster dynamics better. For around $150, you can get an
M-Audio Pulsar II SDC that I liked pretty well - maybe better than the $200 Rode NT5 in this shootout (
http://hearthegear.com/a/66-Acoustic_Guitar_M-Audio_Pulsar_II_microphone.php) . In your price range, you should compare Pulsar and MXL 604 if you have a way to do it.
For guitar and drums, I have to say, though, saving up for an SM81 ($350) or Peluso CEMC6 ($300) would give you much better sound. You might be interested in these mic shootouts on acoustic guitar:
SM57, MXL604, SM81, CEMC6
http://www.ffts.com/music/shootout4.htm
SM81, NT-1a, SP B3, MXL604
http://www.ffts.com/music/shootout2.htm
SM81, SP B3, MXL604
http://www.ffts.com/music/shootout.htm
For recording two or more guitars, or a guitar with other instruments, I prefer to single mic each guitar. I only record in stereo if the guitar is solo, and sometimes when recording one singer and one guitar. Even then I often prefer a single mic on guitar. To do M/S recording, you will need a Figure 8 mic (M/S stereo sounds pretty good on guitar). In your $ range, the M179 (LDC multipattern) and MXL 604 or Pulsar II (SDC) might give you a budget M/S setup.