For someone who doesn't recommend SLI/xfire, I been using it for a month on and off, just cos the gear was laying around. Don't/haven't experienced any stuttering.
I do often think of how builders/users have their rigs setup, as far as Windows/apps are concerned. Many of them use their computer for everything, and can have everything running in the background (all the little checking for updates/devices parts) whilst gaming. I do have the advantage of using the gaming computer just for gaming and absolutely nothing else.
Personally, if I'm buying a new bunch of kit, for a fair sized build, i.e. 3x screens etc, I'd insist on nVidia because at the end of the day I want every game played on it to have, full detail and physx whenever required (without relying on the cpu for it).
If it's a one off card for not a big build, I'd recommend the card, AMD/nVidia depending on the person's budget per fps. But, if there's a big spend, or big build involved, I'd want all graphic options available and all the qualities.
I've never personally understood the purchase of a.... 7990, for example. Why spend all that cash and have a rig that doesn't do everything ? Pure fps yes, but not everything.
Not had microstutter tho. Ever. On anything.