It is really easy to over think all of this. Back when I started playing professionally in 1963(?) all we had was Shure Vocal Master ... it worked great and it still does. If you are playing a large auditorium or a stadium the requirements are bit different. For the average bar you really only need 300 or 4ooW and a powered mixer. I go to some of the local watering holes and these guys are carrying around enough PA gear for a stadium. Like we gotta mic the drums in a 1200sqft room and have a 5000W PA with a 32 Channel Mixing Board two 16 channel snakes and 32 mics, sub woofer, monitors and a sound man and an 18ft truck for a 5 piece bar band making 5 bills a night. Insane. With all that is going on on your average gig I don't really think the PA is a big factor.