Dynamic balance on geared engines

After flying in Ben's and Aaron's planes, I felt like mine wasn't quite as smooth. Ben's is ridiculously smooth, like turbine smooth. Aaron's is also super smooth. Mine was fairly smooth but not like theirs. At cruise I felt a slight vibration in the yoke. I'd heard mixed things about dynamic balance. Some said it was BS... some said you can't dynamic balance a geared prop, especially if there is any slop.  

I talked to DynaVibe who make the tool. They referred me to a shop just 20 miles from my home base. I called the guy and he said it would work. He hadn't done a TwinBo but had done 421's. Said RPM's are RPM's... well for $400 /side I figured it was worth a shot. It took all day with about 5 runs on each engine. Right side went from .4 IPS to .02. Left side went from .1 IPS to .02. Flight home no more vibration in the yoke.  

I'll have a longer flight on Weds to test. What say you, $800 down the toilet or $ well spent?

no reason for the attached photo other than I took it while waiting around...

Contact info:

Tracy Van Iwarden
Aviation Specialties
(707) 451 2860