Situations where you don't have a COR, then Fusen. (Path B) is a worthy and swift blade..
In situations where you have a critical window of time to end a battle with an incredibly powerful Fudo.. Then switch to Fusen. (Path C) to unleash Sekkanokki'd full power Fudo at 3k TP to annihilate the enemy and all of its surroundings..
On many NMs I've reached 90k+ Tachi: Fudo and not even fully buffed...
This is why many of the SU5 blades are worthy of being in their own class as legendary weapons.. They can do things that REMAs can't.. Another great weapon to add to your arsenal for certain situations if you have the gil..
Which by now everyone should..
The Acronym of a Completed SAM =
A-D.R.E.A.M. - SAM
A=Ambuscade (Polearm)
D=Dynamis SU5
R=Relic
E=Empy
A=Aeonic
M=Mythic
.. ^_*)