Think about this, if they had been very good, they would still be avaiable. What you are basicly talking about die stamping. One account I read about some one going into kitting planes recounted the learning curve of sucessful die stamping. That include finding out the you could only die stamp set wet balsa as the dried stuff broke when stamped. Just imagine trying to "clean up" some notches in previously stamped balsa that is dry, or the warpage of soaking it to the point of being able to re-die stamp it and then drying it under uncontroled conditions.
I'm astounded that the die stamped stuff came out as well as it did after reading that article. Fine sanding and or fine tooth cutting is what is called for. This is not a case of "if it doesn't fit, get a bigger hammer"
Balsa is not an easy wood to carve or cut. It is deceptive as it is so soft that some things can be accomplished with a fairly sharp blade. Not always though. Those of us who grew up building 10 cents Comet kits and using double edge razor blades to try and cut the printed pices out of what varied from hard as oak on one end to soft as a cork on the other wood really appriceats the laser cuting and the tools avaible today to work the wood. Chisels was never one of the sucessful methods.
Don