Thank you so much! I could never afford any gold to join gdkp and my guild only did 9/13hc so im very happy i can buy sinestra items soon!!! 
sinestra items is a bit much but w/e.
That would kill Cata even faster, than constant bugs at ever major and minor patch release. I mean why try harder bosses if you can have all loot from them a month after phase ends? This would spawn a lot of seasonal lazy players and would lead to LFR like behaviour and eventually Blizzard would have to release LFR for this type of fed and lazy players who do not want to put effort but want everything from the game.
Alpha heroics gave you second grade gear like t7 200 ilvl (25 normal t7 raid gear) and 25 normal itself gave 213 ilvl from 25 heroic raid during phase 2 of Wrath of the Lich King Classic. Both were worse than Ulduar 10 225 ilvl, yet you had to visit Naxx raid at least to catch up to go to Ulduar.
Why would it kill it? I think its great to give everyone a chance to catch up to Tier 11 bis before FL Raid opens so its an equal playing field! Lazy players? I have to grind tons of heroic+ to get enough stones for all the sinestra and 372 loot i need.
I mean i feel sorry for everyone who spent so much money in GDKP this tier to get full bis and feel regret now that they see that they would have become full bis before next tier 12 anyway due to catchcup mechanics that we all knew was coming!
I was really tempted myself to buy gold and join a 13/13hc run on gehennas my realm since im stuck 9/13 and too far behind that any group would let me join without the xp but i knew catchup mechanics was coming and now im paid for my patience 
I think its great system by blizz to even out the playing field before each tier so people feel a reason to stick around and not falling too far behind! <3 A very inclusive and smart move and im thankful for it!
Look GDKP are cancerous as well, but guilds, like ours, who are not top notch but still clear whole content have problems with reqruiting due to population of the game becoming too volatile. I am all for moderate catch up, but hadling out 379 gear is not a catch up.
You can start Firelands normal raiding with all 365 loot given to player by Molten Front and Halloween event with the rest being mix of 353 from ZG/ZA, normal raids and couple of 372 ilvl loot from easiest heroics. If you managed to get at least half of your gear to 372 you can start strait up in Heroic FL as bosses are in semi post DS patch nerf state (except for Ragnaros) on the PTR.
It doesn’t matter if players would have to do hundreds of heroic+ runs, Blizzard are still not giving player raiding environment experience and promoting abandoning of the game untill next patch catch up, instead of tries and eventual progress on top of the tier bosses.
Shouldnt have added Sinestra loot.