Pro's and con's of Oly's flash system vs Nikon's, or Canon's

The more I shoot, the more I recognize that I will need a flash system (three or four strobes). It will need to be highly portable, easy to power, amazingly versatile, irreproachably reliable, and, of course, cheap. I could really use some advice. I have an E-M5 w/the little flash that came bundled. I have the panny 20/1.7, the oly 45/1.8, and the 12-50/slooow-ride. I know I'll need another lens or two (or twelve), and could get the panny 35-100/2.8 for flexibility, or the oly 75/1.8 just because it is so darn wonderful at portraits (one of them) pretty much right away.

I'll be shooting family portraits, birthdays, indoor/outdoor events, and the occasional wedding(who knew?). I shot an outdoor wedding a few weeks ago in Savannah (it went well), but I realize I'm not prepared for a dim church or reception hall...which leads back to my original request for flash advice. I know about the new 600r, but read that it was flawed in some way, something about the video light and also remote control (like pocket wizard) was problematic. I've also read that Metz were used alot. Any advice or suggestions are very much appreciated. Thanks...