I haven’t done the maths, but I figured that getting Devilment boost on Flourish procs would be more overall DPS than Quadruple Technical Finish.
Though if you get a direct critical hit on Finish, it very well could end up being stronger, but I can’t say if that would make up for the 3/4ish GCDs where Devilment ticks down but you aren’t outputting any damage.
And since I’m not able to check what the GCD potencies are, I know you’d have to deal around 1500+ potency worth of damage in those 3/4ish GCDs, which I’m not even sure a Dancer could do without some super luck with Sabre Dancer
Honestly though, I’m terms of ease-of-use in rotation I find it slots in the GCD between Standard and Technical Finish perfectly, then you can use Flourish after Technical Finish and go straight into using all the procs / Fan dance etc