I used some back of the envelope ratings for feral druid dps (1 str = 1 agi = 0.8 crit = 0.7 hit = 0.42 AP, and I know hit is too high) and the results were quite good. I liked the fact that I could quickly change some ratings and see how it would impact the rankings - this is in particular very useful for capped stats such as +hit in my example, which can go from a high value to 0 depending on other gear.
I also liked the idea that I can assign low but meaningful value to desirable stats (e.g. sta in dps gear) so that these stats would provide the edge between 2 comparable items in terms of dps (in which case the deciding factor is indeed for me the higher sta). For example with pure dps weights I correctly get Haramad's Bargain as one of the best dps options for a cat, but with a little something in stamina then Mithril Chain of Heroism is correctly ranked slightly above - this kind of dynamic rankings are very nice.
A few comments:
- if items drop in 2 different locations, they appear twice in the list, which is not practical (e.g. Skulker's Greaves)
- the items with unknown provenance appear only in the middle raid list, even when they are t4 or pvp items that can easily be accessed at low raid level
- no support for weapon skill
- feral AP not taken into account, which means Stormherald (42 agi and str) and Terestian's staff (37 agi, 38 str) are roughly on par when the second one provides... +671 FAP. That's not what I'd call negligible for a druid

- no way to tell the application to disregard BoP crafts or to explicitly say which professions should be considered for such crafts (for e.g. I'd like to add Alchemy to see how the Alchemist's Stone ranks, but to exlucde all BoP LW items since I'm not LW)
- as usual trinkets (and pretty much any item with on use/on hit effects) are hard to rank but that's always the case