You don't Win against Priests period. Shadow will melt your face off right now at 80. Offensive dispells alone will own you.
Wrong. You can beat a equally geared priest. For starters, why would anyone use SoR in PvP? SoT is better, even if you don't have a full stack. When fighting a shadowpriest, don't pop your wings at the beginning. It's going to be a drawn out fight. As the fight begins, you can do decent damage to them with CS, Judgement and Holy Wrath. They will for the most part always psycic horror you. Don't trinket that. If you do they will get a full fear duration. Eat the PH. After that, flash heal or WoG yourself. Play the battle thinking defense at first. Pick away at them with CS, Judgement and Holy Wrath. They will eventually disperse. When disperse is gone, continue. When they get about half health and you have 3 hp stacks, that's when you repentance them. When they are CCd, that's when you pop wings and zealotry. If they happen to pop their trinket on repentance(only bad priests would trinket repentance), immediate hit them with hammer of justice. If they don't trinket repentance, you'll get a HoW off on them. Then you immediately HoJ them. They key is to never ever pop wings unless they are CC'd or stunned and not until they have about 50-60% health. When you get a HoW off, CS for 3 stacks of HP and TV. Don't listen to anyone saying a ret can't beat a shadowpriest.
I have like 3 priests and a Ret so I am very familiar with the play and mechanics of Shadowpriests. Every shadowpriest I go up against follow the same routine.
No way does this work, every priest that I've fought has been either a straight up asskicking, either in their favor, or mine. I have yet to see a middle ground fight like you describe. Basically what happens when I get my as kicked is they basically out heal my damage with VE alone, their bubble never fades, and I'm taking too much damage. These aren't even Heroic geared priests which is bothering the hell out of me, I'm getting destroyed by priests in freaking relentless while i'm sitting in just about full wrathful sans shoulders and weapon. I don't understand where this damage is coming from, or why people keep suggesting what you said. Its not working for me. At all. If I could actually draw the fight out, then maybe I'd believe you, but right now I'm borderline globaled with ~1300 resil, with dots alone taking me to 50% over half way through there duration.