the main reason for the 2 piece driveshafts is to eliminate the imbalance issue. Driveshafts have a critical speed where they vibrate themselves to death. Stock 1 pieces ae most likely only balanced up to 100 +/-. I know this first hand as my driveshaft went out on my truck at 122 on the dyno. The only trucks with one piece driveshafts that GM produces these days are std cab, short bed. Food for thought. Safety wise, I think you are better off with the 2 piece.
Andrew