Just my 2 cents but as a GM of a casual guild, I was very happy when I found wow-heroes.com and am extremely satisfied with the current valuation of PVP and PVE gear. I used to use wowarmory but the last couple of months have used wow-heroes to qualify people for my PUG raids. My brothers, rl friends and I (the officers in our guild) are more competetive players than most of the 300+ members of our guild so we really enjoy the end game content but also really enjoy being in a casual guild without attendance requirements that turn raiding into a chore instead of the fun it should be. I can say, in respect to PVP gear ratings, that say for a kara badge run (3 hours pre-patch) when wow-heroes gave the prospective raid member a score of 500+ (not uncommon for someone with several S3/S4 pieces) we have NEVER been disappointed with their performance as it hung right there with anyone in T4/T5 that would have a similar score on wow-heroes.
Obviously it varies by class, but hunters are THE prime example of a class that can do full t5/t6 runs in top end PVP/arena gear without any problems at all (but far from the only class that can pull it off with the playing ability that one inevitably gains in the pursuit of such a set of gear). You can check out Epicac from the realm Dalaran for an example, I have banked my t4, top end badge gear (even from the isle) long ago and will only run him in PVP gear as I pick up several thousand health, a dozen or more percent crit and even a slight base dps increase. Pre-patch the only difference from my "PVE gear" I made was I kept aspect of the viper up instead of hawk to improve mana regen in anything less than a 25man raid. To further the point, I have run BT with Natural Affinity (pre-patch) which is one of the top raiding guilds on our server (13 I think on wowjutsu) and was 3rd on the damage meter only to 2 other hunters again while wearing 100% PVP/arena gear. I'm not trying to brag, just supporting my assertion that PVP gear DOES have significant value in the PVE world despite the fact that some people who spent hours upon hours raiding for PVE gear feel jaded that a person in arena gear can out score them here on wow-heroes. The proof is in the pudding and I would remind those raiders that you don't get a set like Epicac's in any short amount of time, either; I likely spent as much time or more on that set of gear as I would have in raids trying to get a mostly t5 set up.
Anyway, that was more than 2 cents but you get the picture. And thanks for the great work on the site, guys!
Epicac/Theprophet of Dalaran