As most people probably know, except for your gimmick builds (Air smiters, etc.) most balanced GvG teams use a pair of adrenaline spikers as their primary damage dealers. It's the classic charge-and-spike combo for warriors... so why isn't Sympathetic Visage more popular?
With both Sympathetic Visage and Ancestral Visage, a mesmer (or even a non-mesmer) can keep up the defenses on multiple targets at once. All he has to do is watch the warriors, and when they start charging on a target, just put Visage on the target and watch as the entire spike gets shot to hell. Axe spikers are back to square one (or square zero, now they have no energy for Shock either), thumpers can't charge for their KD, and assassins (though I see very few assassin spikes in GvG) will lose the majority of their energy in seconds (less if there are multiple assassins).
In the event that Visage gets stripped or shattered, you have another as backup. Besides, it would difficult to strip Visage before an auto-attacking warrior makes a hit.
I'm sure there's a perfectly good reason for my rarely seeing Visage, as it just seems way too obvious a counter. Any takers?