dexos1/Gen2 & GF-6 (not even here yet) are late to the timing chain wear test party.
Two tests, the M 271 Wear Test & the OM 646 DE22LA Wear (CEC L-99-08) Test, are in MB 229.5 and have been there for years now.
As for whether dexos1 Gen2 timing chain tests are "working" or not, as somebody above thought, its too early to tell. dexos1/Gen2 just hit the shelves.
I thought the GM 3.6L engine has suffered from occasional supplier problems in surface hardening the timing chains. When they surface harden correctly, those things last. Should only be afflicting 5+ year old 3.6L engines.