Well if an oil spec meets or exceeds porsche / mb standards and dexos 2 I'm going to bet its higher grade than just an oil that meets dexos 2...
But thats not even considering the kinematic viscosity at 100c, the shear point or the pour temperature...all of which I look at before buying.
If you live in the uk, when are you going to hit temperatures cold enough to notice the difference between -45 and -48 pour points?
Also if you have a look at the viscosity index of the oil, you'll see if they've skimped on the VI improver adds.
The shear point will be irrelevant if you leave the oil a long time between changes às well.
If you have a dpf fitted you might also want to have a look at the saps level in the specs, especially if the wording "lower" ash is used.
New spec changes that came into force last year reduced the ash levels to 0.3? From the previous 0.5 level.
Obviously not every car needs it to be this low but like the wording "meets spec", lower ash is a sneaky way of making you think your buying the best stuff.
Do you check the HTHS and TBN values as well?