You guys are pretty lucky in GHQ. I just leveled up, so I spent a little over 400 stamina in GHQ and there were 3 times that I didn't get a triple hit. That being said, I still think GHQ is far better than the BA since it's possible to spend tons of stamina and not get a triple hit. The odds are just far better in the GHQ

However...because the GHQ is expensive, it can be difficult to get the triple hit that you are aiming for. From personal experience I have noticed that EXP hits seem to happen more in the BA while Chance and Pero tend to happen more in GHQ. This of course is just my personal experience and I don't have solid numbers to hand out aside from what happened to me today....

Spending 440 stamina I have hit these numbers in GHQ:

Chance: 7 times
EXP: 2 times
Pero: 4-5 times
Gift: 4 times
Miss: 3-4 times

This is just today's results. Yesterday I did hit EXP more often, but certainly not as much as the BA.