i don't have a problem with congregational prayer at all, alzado. and, i agree that we should have a certain deportment when we come before God in that context. what i disagree with is to say 'this person has piety.' and 'this person does not.' when, in actuality, piety is a very unknowable thing to us. can we know what each person is thinking? what if a person is daubing their eye because of allergies. i know this is kind of a silly way to put it - but we really don't know their hearts.
appropriateness is always a pleasure to see though. i'd prefer to use the word 'devout.' a person truly believes what they believe. this is just a matter of preference though, and i admit that you may have a point about what is appropriate in what setting.
i personally appreciate it when people dress for an occasion. sometimes, my daughter wants to go to church in jeans. i just don't think that's appropriate - but sometimes i get my way and other times she wears just a nice blouse and still wears pants. being somewhat old fashioned , i see your point about piety too. to me, for men and women to worship together according to a set and orderly religious service appeals to me much more than pentecostal ways, too. but, maybe there's a time and place for 'feelings.' i think it's hard to tell sometimes until you are 'moved' yourself to sing louder, sway to the music, or just make smaller gestures of a more personal nature as you mentioned. if we can be excited by music itself - and God is the creator of it all - however we express our happiness should be fine.
king david danced enough that his wife told him she thought he should stop. did someone see his underwear? was he wearing a kilt? i don't think God minds enthusiasm - it's probably that as humans we can get caught up in the moment of whatever we are doing and have noone else to answer to about our sincerity but God.