They DO have a shitload of issues with chains. Early models before chain design revision are pretty well guaranteed to have troubles, and for the later ones it's just luck of the draw.
They're just a poor design. You need to rev them much harder to net the same result as the earlier ecotec. Any mass produced car that needs servicing at 5000km is a joke. They require over 6L of oil for every change, and fully synthetic oil at that. Incredibly inefficient in terms of repair costs (chains, spark plug changes, oil changes and pretty well any other repairs that may be required) due to their design.
Holden REALLY dropped the ball with their decision to run the alloytec. Historically, the engine offerings in commodores were pretty well bulletproof, easy to service, repair and rebuild with little to no special knowledge or tools, AND parts were cheap and accessible. A big, heavy RWD car sold to Aussies who are notoriously hard on their vehicles (not to mention the climate and road conditions) was an incredibly poor move. Sure, 175, 190, 210kw power figures sound good, but torque figures and the rev range they're achieved at is a joke.
Hence the second half of the comment. If you want an absolutely bulletproof engine to mod and aren't willing to go through the dramas of an Alloytec, go with the Ecotec.