I've tried many different makes of cards in the past, and my vote would have to go to EVGA for the top nVidia cards. Asus makes excellent cards with the DCUII line, but that aren't really aimed at the top end of the enthusiast market it seems... The larger air coolers on them with a triple slot design pretty much limits them to two way sli as the maximum, because three way bridges just aren't long enough, even using flexible cables instead of the pcb bridge, this means the cards are limited to people looking to run only a single card, or two way sli at the most. The lack of a water cooled version of this card also puts it more towards the upper mid range demographic (air cooled systems), rather than the top level systems that have liquid cooling.
EVGA also adds more VRAM to the nVidia cards (which I think are significantly lacking in this department) which improve the performance of people looking to run at very high resolutions, if you are buying a set of top of the line cards that cost 550+ each, you won't be running a single 19" low res monitor, so this would apply to a large majority of people looking at this price ranged card. 2560x1600(or 1440) monitors are more and more common now, with some very high quality ones available for ~300, hardware needs to keep up with this, so when you are buying top of the line, you don't want something that can't handle it because it lacks vram. One monitor at that resolution may be fine for many games, (I capped the 2gb vram in BF3 and several other games with just 1 monitor, so more would help even with just single display) but anyone looking to push surround with more than one of these will have to look to EVGA for their 4gig fix. You can get a 4GB FTW+ card for $609 right now, which is only $40 more than the DCUII cards, so the extra ram can't cost too much to implement. 7680x1600/1440 is just not possible with asus cards.
That is the main thing I don't understand. Asus pushes the boundaries with all the bells and whistles on their motherboards, giving support to extreme options like sub zero LN2 cooling, 4 way SLI, watercooled VRMs/chipsets, and other enthusiast oriented extras and tweaking options, stuff that only those using the best of the best would use. But then even the best of the video cards are just aimed at the average casual user, someone that would just plug it in and go, nothing really oriented at a tweaker or enthusiast user. Maybe you could adopt the motherboard system for your cards, a Gene model for more casual use, Formula for gamer oriented, and Extreme for enthusiast. Like the reference clocked, or the DCUII OC can be the MATRIX680-Gene, the TOP can be the MATRIX680-Formula, and they you can introduce a 4GB waterblock version as the MATRIX680-Extreme or something similar. Right now it just feels like the Motherboard and Video cards are from two completely different companies, your motherboards are the best out there, but your video cards are just middle of the pack. The build quality is there, but the feature set just doesn't really distinguish it as a top end product.
I'm using the DC2Top cards now, and that's just how I feel after making the purchase and having used them for a while. I think that seems to be the general perception of a large portion of enthusiasts as well, people looking to run multi monitor setups or watercooling, or 3+SLI go with EVGA, people looking for a top quality tweakable card go with the MSI lightnings, people looking for quiet and cool cards that they can sli go with the gigabyte windforce cards, people that want just a single card that pretty good out of the box go with the asus (theres nothing wrong with that, but it just doesn't seem like thats what all the other RoG products aim for)
CM Storm Trooper
Rampage IV Extreme
3930K@5.1GHz 1.48V (+0.085 Offset) XSPC Raystorm +Alphacool 360mm UT-60 /w 3x Scythe Ultra Kaze @2200rpm
Asus DC2T GTX680 x2 (going for a 3rd with some EK blocks when the budget allows)
32GB (4x8GB) DDR3-2400 G.skill Trident X
2x 256GB Vertex4 Raid0
Seasonic Platinum 1000W