I'd highly recommend getting a quote from someone who uses the Farrow System http://www.farrowsystem.com/
. Just had my bottom done for $26/foot and was pleased with the results (of their work). I gotta do a good bit of tiny blister filling, it looks like by bottom has a case of the measles.
Seems that this system allows the user to control the cut very well. Something to do with the low pressure (40 psi) and the fact that the media is very fine. All my bottom paint was removed leaving the barrier coat intact.