It's definitely worth it

 

I imagine soda blasting would work well for cleaning pistons. For a good deal on an ultra-sonic cleaner, look up sites that sell used lab equipment. A used good one is better than a new cheap one.

 

The ultrasonic cleaner solution sounds like a pretty good idea. It sounds like it's non-destructive, anyway.

I had mine soda blasted to remove any metal flakes from the skirts.

Be sure that the ring grooves don't get blasted. They should be taped off all the way from the piston face to the skirts so they remain sharp - if they're dulled, I've been told it makes for a "tired" piston.