Yea with the Mitsi's you don't have to balance them when removing the balance shaft as engine rotating mass balance is different to what a balance shaft is trying to equalize, balance shafts are really there for driver comfort/smoother engine. I sell Mitsi Balance shaft removal kits i.e frost plug 2 threaded plugs and another size frost plug, and most people I have sold them to have just pulled it out plugged it up. I know its not much use cause were talking about Holden 3800, but they do the same job.
*EDITIf you do balance them without the balance shaft it'll be a bitch to get the right balance ratio but can be done, not by the factory specifications as they will be wrong without the shaft.
and....apparently you gain HP in the 3800 because there is less drag on the timing/drive train sides of things, not sure about mitsi's on that one as most run a separate balance shaft belt.
So in short go for it if you want.