To sum up the pallium was an ornament of metropolitans given to perhaps from early times by the patriarchs and by the Pope in that comparatively narrow district which was his most immediate supervision the Pope gave it to his vicars in parts then as a mark of special dignity to some bishops then he required Western metropolitans to ask it before exercising their functions and finally the rule extended even to patriarchs
I would suggest that he continue to wear the omophorion he already wears over either the byzantine or Latin rite vestments, because I agree that they are the same vestment, only different styles. This is quite an interesting question !! The paradox of diverging developments for the same vestment presents itself as confusing when the two rites try to come into harmony with each other.
The issue would seemingly be more confusing were there to be bishops who are exclusively ordained for the latin/western rite of Orthodoxy. While, they would by the the basic nature of the tradition of this particular church, not need a pallium or have traditionally one that is necessary, they could be given one as an honour by the ecumenical or other Patriarch . This would serve a useful purpose because it would make it clear to the byzantine rite laity that they are bishops of the same status as byzantine rite bishops. So much like the fact that married men are by default allowed as western rite orthodox priests when they had not been within the Pope of Rome since the 5th century granted this custom. Married priests could legitimately be called a revival of an earlier practice (as mentioned by St. Patrick in his confessio that he is the son of a deacon and grandson of a presbyter), the use of pallium by regular bishops could be seen as harmonization as mutually enriching practice of the byzantine rite, applied to the latin rite. A "byzantization"
probably it would be, but does that mean it is a bad idea developing? Not necessarily, though certainly this concept is controversial , it is not something absolutely taboo.
It is very true that the average bishop did not wear a pallium in the west.
However, before the 12th century there were hundreds of bishops who were given the pallium as a special honour. This is the practice that disappeared largely after the centralization/authoritarian policies of the gregorian reform manifested themselves. I know this because the iconography of manuscripts and frescos of this time period shows a greater frequency of bishops wearing them than does iconography from after the 13th century, when gothic/humanism/scholastic influences combined to transform and wash away key elements of the earlier latin church traditions. It was particularly common for a great number of the non-metropolitan bishops who became saints to have been bestowed an honourary pallium. This also is partly why they became saints, they were already acknolwedged as being very loyal and holy, therefore they had a pallium. The clergies favourites often had an easier time being canonized more quickly than those that were not their favourite.
Therefore if hundreds of bishops were bestowed the pallium as special honour, it could I think be argued to be possible to be a development within Orthodoxy that all were granted it, though by no means would it have been tradition for typical latin bishops in ages past to have had this, only exceptional ones.
I once read a very good detailed enclycopedia article on the pallium. It is a little known, frequently misunderstood vestment, especially it's history before 1054. The subject deserves further study by others.
