Originally Posted by Aeolian
Note that the Beta's are hyper-cardioid while the SM's are conventional cardioid. I think that accounts for the somewhat thicker sound I've gotten close micing a guitar cab with one. There's a slightly greater high end to them. I've actually used them as single overheads in small live situations. Hung over the snare they will predominately pick up the snare and enough cymbals to get a nice bit of reinforcement to the live sound. I think the combination of the natural HF limitations and the tighter pattern play out well here. For recording a snare, it will be more placement critical but also have more rejection, helping to keep the hat out of the snare mic.
Realize that hyper-cardioids pick up from right behind the mic. The biggest null is off to the sides. This is a pain in live work when folks lean down over a floor wedge with the mic pointed exactly away from the wedge. Contrary to what they expect, it feeds back. You need to keep the back of them off axis from the wedges. I try to stay away from Beta 58s for this reason. Some folks are addicted to the presence of them, and if I can keep them on the stands pointed flatter, it can work. But have someone start carrying them around and be careful.
Hyper cardioid mics work well with pairs of wedges that are separated (mic stand in between) and are fantastic for fixed backing vocals. On the other hand for hand held applications where the vocalist moves around and is using wedges for foldback, often a cardioid pattern is a better choice (less tonal variations to deal with if the singer changes the angle and or distance from the mic, and less problems with 180 degree off axis lobes at 5 k etc).
With in-ear monitors, singers become much more aware of microphone proximity/angle variations, and generally become much more consistent with their approach, so this coupled with the reduced need for high levels in the wedges means that hyper cardioid hand helds can be more favourable.