The timing and balance shaft chains on these Ecotecs are very long-lasting, and usually the sprockets don't need replacing - what happens is that the chain stretch plus wear on the guides goes beyond the capability of the tensioner to accommodate. Usually by that point the stretch isn't sufficient to wear the sprockets, so I'd be tempted to just look at the sprockets plus the guides carefully for signs of wear, and re-use the sprockets. There are chain kits including all the sprockets, guides and tensioner, but I doubt that the quality of the sprockets is as good as the originals. At 100,000+ miles, my sprockets appeared in perfect condition. The balance shaft chain has an easier time than the cam chain, and isn't a common wear issue, other than the guides.
The tensioner on the camshaft chain has both a spring preload plus an oil pressure loading, and the 'new' tensioner moves more of that balance to the spring, so that the tension on startup, before the oil pressure has come up, is better - reducing the possibility that the chain will lose tension as the lumpiness of the cams overcomes the preload applied by the tensioner. That's what causes the rattle. There's a staircase type travel limiter built into the tensioner, so it can't be pushed back by more than a certain amount.