As I haven’t used both those mics I’ll let others comment on a comparison. Both companies make excellent products. You won’t go wrong with either. I’ve seen adapters that accept a mic input and then connect to the Mac via USB. That might work better than plugging directly to the Mac.
As for recording in your room, that’s ok. Just do some test records before you record the whole thing. Record with the mic relatively close to your mouth. The closer it is the louder your voice is compared to external noises. As you move the mic closer your voice gets louder, and as you lower the mic gain you also lower any external sounds. Just beware of P-pops or other plosives with close-micing. I know the RE50 has excellent pop rejection. Again, test and listen. Check out how obtrusive external noises are and listen for boominess or a hollow sound to your voice or the room. If you hear that, try different mic positions in the room. Maybe a closet with lots of clothes that would absorb ceratin frequencies and reduce the hollow sound. Or you could close draperies and/or hang some blankets to dampen reflections off the walls. BTW, if you record a take and it’s interrupted by an external noise, or you flub, you can always go for take 2.
John
MacPro 8-core 2.8GHz 8 GB RAM OS 10.5.8 QT7.6.4 Kona 3 Dual Cinema 23 ATI Radeon HD 3870, 24″ TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.1, Motion 4.0.1, Comp 3.5.1, DVDSP 4.2.2, Color 1.5.1)
Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec Monitors, PrimaLT ISDN