849s are suitable both for live work and recording but they are electret condenser microphones and therefore not as physically robust as dynamic mics.

They are suitable for voice but have no mid frequency "presence" peak or bass proximity effect as often found in dynamic vocal mics.

They need phantom power or a PS1A power adapter or an internal battery.

They are discontinued by Shure but there is still a user guide at -

http://www.shure.com/pdf/discontinued/849.pdf

regards
Mitch