The Electrovoice 635A is a unique dynamic microphone.  I have only used the mic in the recording studio rather than for live sound, but I would think that it would be useful in both situations.  The mic has an omnidirectional polar pick up pattern and is hand held, which is what makes me think it would be suitable for live shows.

OVERALL OPINION

I first used the Electrovoice 635A about two years ago and right off the bat I was a fan of it.  While it isn't anything too special in terms of sound quality, it is a sturdy, well built microphone that I think it suitable for a variety of applications.  I only used it on two instruments in the studio - snare drum and electric guitar, but I think that it would make a good vocal mic in a live situation.  The sound quality is super clean, but is very respectable for a dynamic mic and is also reasonable in price.  While it doesn't beat the value of a Shure SM57, it is in the same price range and does have a similar type of sound.  Electrovoice is known for making some very sturdy microphones, and I think that this is one of the best features concerning the 635A.  While I don't think it would be my first choice in terms of a dynamic mic in the studio, it is still a very good choice and is one that should be explored by those interested in a mic like this.  While I do think it would be a great vocal mic for a live show, I would try it out in this application first as I don't have any experience with it in this setting, it just seems like this mic is catered for this type of use as well as use in the studio.  All in all, the Electrovoice 635A is a very strong microphone that falls right in line with the high quality that Electrovoice has become known for.