I've eyeballed that FF CF+Rec many a time for my claws users but in the end, I'd rather just load up on enough recharge to run followup, focus, slash, repeat for my ST chain and followup, spin, shockwave on my aoe chain. That's for scrappers. For brutes/tanks the aoe chain is followup, focus, spin, shockwave.
If I got with the FF proc, I either lose the KB>KD proc or the 10% +recharge from ragnarok. Not sure I'd wanna go that route for 5 seconds of +100% recharge although with shockwave, I can see that being pretty damn persistent. I'll run a test with my claws/fire brute farmer and see how it plays out.