I believe the short answer is- yes it does exist, yes it is (almost undoubtably) active, though it will be around 10x less potent than PCP/PCE. I believe it is a known, patented chemical- though no idea about how much it was ever tested (let alone in humans), but that's how parke-davis does shit.
I reckon it's an avenue that should be explored- 4-MeO-PCP was not a dissapointing compound, it just was missing something. I think there's every chance that one of the 4-MeO-PCX would be a awesome drug with a similar dosage/effect to ketamine. Gimme some 4-MeO-PCE/PCPy/PCPr/TCP/BCP damnit!
But in general, 4-MeO = reduction in potency. It's not known if you can 'boost' the potency (it's not known if 4-MeO-PCE/TCP would be stronger than 4-MeO-PCP, just that it decreases the potency of the mother compound). Also, the change in effects between 4-MeO-PCP and 4-MeO-PCE could be radically different.