Yup. The thing as well, x2 GK-BFB is only worth around 0.75 PPS, which equates to roughly a 4.04 DPS increase. Just a 26 DET increase, is enough to outweigh the gain from x2 GK-BFB. You do need roughly 590+ SS to successfully get x2 GK-BFBs. Let's do a comparison:
http://ffxiv.ariyala.com/TGXH
Weight: 2202.298
DPS: 1940.785613
The only other set with a lower SS, which beats this set, whilst taking into consideration x2 GK-BFB, is this set:
http://ffxiv.ariyala.com/TGXM
Weight: 2205.956
DPS: 1946.271542
Or, the next step is going to near sub 500 SS:
http://ffxiv.ariyala.com/TGXV
Weight: 2204.983
DPS: 1944.964047
Ultimately, you either stick to +590 SS, or you absolutely crash your skillspeed.
Personally, I'm very bias towards high SS builds (680 range), so I cannot comment on which of the sets are better in a Raid Environment.
What I'm personally building:
http://ffxiv.ariyala.com/TGYB
Weight: 2197.302
DPS: 1933.054354