You'll most likely be hitting 180-184 Attackspeed, with that weapon, 99 AGI, and an awake. (I forget, can Sin's use Zerks?)
If you can live with that number, go right ahead. Your crit damage will be fairly good, but I think 190 attackspeed is quite often more
prefered over the increase in damage that you'll get. I'd stick with DDMA, or DDAA, whichever is more useful.
As far as I can see, the damage wouldn't make a huge difference. Of course it'll be alright if you want it for PvM, since you'll be wanting a bit more
Damage for Sonic blow. But for PvP I think 190 attackspeed is more important.
Also - I'd actually suggest getting a DDTP MG, and a fire elemental Dagger as starting weapons, if you have the money/zeny for it.
Of course that's only because it will be more useful to you in Woe. (Emp is the Earth property, so fire will help.)
Of course later down the line you can get a DDTT/DDTP and an Icepick for empbreaking.
But that's only if you're interested in Woe.