Some quick numbers:
From your current setup vs. Suen-wo(522):
MH/OH gains: 401 int, 241 spirit, 357 crit.
Staff gains: 847 mastery, 105 haste, 1376 spell power.
Soulblade of the Breaking Storm(522) + Fan of the Fiery Winds(double upgraded heroic) vs Suen-Wo(522):
MH/OH gains: 30 int, 535 spirit, 431 crit, 1 raw spell power
Staff gains: 172 sta, 847 mastery, 105 haste.
In this case, I would actually go 522 1h/510 OH over 522 staff. I can run some numbers for other weapon combos if you want, though.
The staff is kind of bad, having no spirit or crit(our two best stats), and tons of haste/mastery(our two worst stats), but the raw SP should be a throughput buff over the mh/oh combo. Also, if you shoot for the next haste breakpoint for another ReM tick, the haste might be more valuable to you from the staff.
Edited by Yuenwooping on 3/27/2013 6:37 AM PDT