I recently picked up a soda blaster for graffiti abatement. I havent had a chance to mess around with it because I am setting up my hot water rig right now, but I will post the results on how it worked. I have heard good things about it though.
I have a friend who works for the city near me and she is in charge of graffiti removal and they have used the same company for 15 years (actually they were the first and only company who approached them about doing removal) and I told her about the soda blasting. The other guys are color matching and painting over without even attempting to pressure wash and the turn around time is around 72 hrs +. I live close and will be able to get it done same day. She already agreed that after I get set up, I have the contract, which is rather large, pending the outcome of the soda blasting, so I am keeping my fingers crossed that it does prodice good results.