I am sure that depends completely upon your mana situation as a dps caster/what your group composition is. Pre-2.3, I ran a spellsurge weapon as an arcane mage. I had a boomkin in my group who did the same thing. We saw noticable benefits from it. After 2.3 I understandably went fire
The boomkin just got a new weapon so he put spellsurge on his old one. He is in a group with locks and doesn't get a SP normally, so the added mana on a reasonable weapon makes sense for him. If I get a spare, "good" weapon I will probably do the same and keep it in my bag for those long fights where we are sucking mana at the end. It doesn't happen often but every couple weeks I am in a situation where I am moving healers in and out of SP/manatide and if I had a spellsurge to help I would be utilizing that as well.