Point is, I don't think one should be concerned about D1G3 having a lower wear standard than D1G2.
"NOTE: the relative performance of the dexos® 1 Gen 3 wear specification is ranked slightly lower than dexos® 1 Gen 2 since GM removed an engine test (RNT) and replaced it with a bench test (MTM). Generally, an engine test is a better method of evaluating performance. The specification does still utilize the Sequence IVB wear test, which is also part of the API and ILSAC specifications. "
360.lubrizol.com