500 people?
Hmmm............one Bose tower will more than do the trick.
JBL eon15's are bass heavy, and the horns are too dark
Mackie 450's are balanced and clearer
Barbetta's are punchy and loud, but the high end is harsh
Bose is clear, efficient, but some miss that "thumpy" bass that hurts your ears.
Best advice, like Donny said .... try them all out with your OWN gear. That's teh only way to know for sure. As for your friends who said you need pole mounted speakers to look professional ... well, that's just not so. It may be the norm, or the vast majority, but please ... never go on the advice of someone unless thay are IN THE FIELD themselves. Sound is not judged by looks. I DO admit that looks are important - that's one bonus of the Bose setup - can hardly even see it on stage !