This has been a common topic for debate since RoS launched introducing rifts. From patches 2.0 - 2.1.1 I was always on the fence. I did what ever my group did basically. But in 2.1.2 things changed a lot.
Now that xp gear is working very well in high grifts AND rg loot/mats/bloodshards drops have been improved for high grifts.... There is no reason to farm your gear in t6.
For all those wondering if u get more legs by full clearing or closing, I respond with who cares? Neither of them yield more legs then speed farming grifts.
For me the loot in t6 rifts is irrelavant. I am ONLY doing t6 rifts for the trial keystones. I recommend everyone else does this also. Once you've stacked up your 25-50 trial keys you don't even need to do anymore t6 tbh. U can recycle your keys in grifts, which is something you can not do in t6.
Basically I'm saying that t6 rifts are just another chore (similiar to bounties). The real loot is found doing grifts. Open the rift, kill the rg, get your trial key, close, and farm loot on a real mans difficulty (grift 34-37).