I've been using the WA-251 primarily for vocals, acoustic guitar and as a mono room mic for drums. 9 out of 10 times it's running through a Focusrite ISA pre-amp, usually on the '110' impedance setting, just for full disclosure.
As a vocal mic it really stands out - it's rich, warm and bright (but certainly not harsh). I've primarily used it for male singers in the baritone-to-tenor range doing rock-ish songs. I've done occasional work with female singers in the pop and jazz genres and it works like a charm here as well. Proximity effect is negligible and a well-schooled singer can deal with any problems that may occur. No sibilance issues of signficance either.
For acoustic guitar the same qualities shine; it's rich, full and warm and bright enough for that really 'expensive' sound. I've usually got it set up around 25-30 cm's away, pointed towards where the neck meets the body, using the cardiod or omni pattern. It sounds amazing.
For drums, I like to put it 5-6 meters out, at about 2 meters height, angled slightly downwards in the omni pattern. If the drummer is a cymbal basher, I'll put it around hip-height instead. Clean, crisp wonderfull image of the full kit.
Pro's: It sounds AMAZING! I know it's not cheap, but it sounds much more expensive than it is. It's a beautiful vintage design to look at, but the sound is what matters, and it does not disappoint.
Con's: Takes 10-15 minutes for the tube to fully warm up. Usually not a problem in a session, but it might bother some.
I highly recommend this microphone. If you're considering this mic, odds are you've been looking at the WA-47 as well. I've auditioned both and for my applications the WA- 251 won hands down.
