first of all a mmo game has to be perfect for both PVP PVE
If you ever find that mmo let me know!
OT: during my years i've never really have had or have seen an issue getting runs with an odd combo. just find the right folks to run with.
But if you go with odd combos then you will be useless When i started the game ppl told me only play Warrior/mage for dd or scout, otherwise you can't join runs. (WoW classes are perfect for PVP PVE and it has meta function, they always update classes