I read a lot of reviews on rockwell, Dremmel and Fien... I bought the Rockwell as a more durrable but less expensive solution for my occassional DIY needs.  If I were a pro I would consider a Fien.  I do not have great expectations for speed with the sonicraft...I have used this form of vibrating technology with other tools... none are very quick. But lets not set the bar to low.  The speed is reasonable and it is acceptable if it saves any time in excess of available alternatives.  I find the tool usefill for tight jobs or those jobs where considerable deomolition and rebuilding is relatively greater than the actual outcome deserves.  Others I know who own ths tool think it does a great job on grout and tile work.  This blade is most usefull for some cuts, especially if the straighter blades won't reach the job properly. I have several of each in my tool kit and use what is most appropriate.