From a detergency standpoint dexos1 Gen 2 would probably perform similar to GF-5 or GF-5 plus in standardized testing.
An additional area that was focused on was chain wear - which the new dexos1 formulas could protect better in this regard than the current GF-5 formulas.
I know that some additive companies are offering stand-alone packages for the new dexos1 only, where some (like Afton) have indicated that there is possibility to use a GF-5 additive package and then add a booster to get to dexos1 performance.
That tells me that although the core components are the same, dexos1 requires a higher concentration of some additive components to meet the performance testing required by GM.