Topic OK, so I took a risk and...
It paid off.
This week in LFR, I have had unnatural good luck and got several gear drops from ToT bosses.
I was at a crossroads where I had the T14 2 set bonus (15% inc dmg on TV) but had gotten better 502 gear from drops. I took the plunge and actually replaced my set bonus gear. I tested myself on the test dummies, unbuffed, and saw an actual dps increase (though marginal, around 3 or 4K).
Then I ran a heroic dungeon with a guild mate who consistently out dps'd me by 5 to 10K per boss fight on most of our runs together in Heroics, LFR, and Normal 10 mans. We got Shado Pan Monestary where instead of my normal 60 - 70K dps I averaged 85 - 90K dps, including over 100K on the first boss.
While I'm not completely sold that I made the right move yet, I am very happy with the results so far. I plan on running a couple of LFR's today before my guilds normal 10 man run on ToT tonight.
So far... so good.