The theoretical 40 DPS higher does not make up for the 200 lower rDPS. In any fight that cuts it close, that will always be the deciding factor. Once people get better that won't be the case, but in progression it will always be the case.
This was formula'd on the japanese forum ages ago:
http://i.imgur.com/uiGorh5.jpg
I ended up doing an extremely shoddy translation job but I can't find it. But when you take numbers of actual uptime it differs from this images uptime
i.e; 15% hypercharge for Susanoo
25% for Lak, Alte, Onslaught, and hali
Which is indeed accurate for the post that you pulled out of discord (that being a 1.25% rDPS increase for MCH and near double for BRD). You can do the experiment on your own and pull form the middle 30 to bring up the numbers and then average them which will still give you a near 25% uptime which leads to 1.25%.
Naturally that ends up being tight right now. On the topic of DPS, i generally bring 3.8k-3.9k to most of the fights while also fighting against slightly more lag than what a normal player would face. That said, that requires as good of a rotation I can think of while also keeping up mechanics
