I love it when Brent does my job for me…because he does it well. 
I’ve been so swamped today I didn’t see this til now.
UB I’m not offended at all. While I’m sure you could come up with an offensive question, ones about why we do something a certain way on a customer car should only offend a shop if the shop did something they shouldn’t have. That assumes you don’t ask the question like an ass…which of course you didn’t.
Anyways…on a DSM many (dare I say most?) people that build them up remove the balance shafts without any issues. We make sure the balancer is balanced and in good shape, we make sure everything we put in the engine is balanced extremely well, as well as the clutch/flywheel assembly in many cases, and they should be good to go.