I now feel like a hypocrite. After a lengthy period of time where I stayed hacked off with other guilds who used the Gear Score yard stick to measure up people for raiding, I found myself using it as well. I do understand that GS doesn't equal skill, but something I've come to realize over the past month is that with ICC, those instances can be a serious gear check.
What's a gear check you ask? Let's examine what our gear does for us. I'll focus on a class I know well right now. The Mage.
I won't go into too much depth about specs, but I use Arcane right now. Arcane depends on several things and yes, we of the Arcane variety could argue day and night about what we think is most important. What I'll focus on here is Haste and Crit. Haste lets me cast much more quickly than I normally would and of course, crits make my spells hit harder. Combined, you have a great deal of DPS dealt due to the speed increase and crits hitting. In a 25 man environment with all the buffs, I'm sitting at 50% crit and about 535 Haste which means I cast 16.35% faster than I normally would. The lower my stats, the less I'm doing overall, which means that under most circumstances, the raid would struggle to make up the difference. More time in a boss fight equals failure usually. You have to deal with enrage timers and the ever decreasing mana pools of casters and healers.
So yes, I'm using GS as a simple measure how someone can hang with the group during an encounter. Of course, I don't use it as a end-all of measuring sticks. I've even taken someone with just over 2k GS into an ICC 25 rep run and into ToC25 to clear. I think it simply depends on how the group works together and knowing each member's strengths and weaknesses.