I bought a new chain and sprockets at about 18,000 miles but just now replaced them all at 24,000 miles. The chain was pretty "loose" and wasn't lining up with the sprockets too well. I had a Scott oiler going for the last 16,000 miles and I think it helped.
The rear sprocket was still pretty good, and the front was slightly distorted, but not as bad as I have seen. Even so, it would not be good to use it with a new chain.
The new chain, DID 525VM X-ring is beefier than the stock chain and should last quite a while with care. I measured the links (inner and outer) on the stock as 0.078" and 0.079" and the DID was 0.094" and 0.087" thick.
Everything is quieter and smoother now - no surprise.
2004 dl650-the urban warrior.
2007 R1200RT - the highway beast