Combinations - Venlafaxine and Methadone

[baron samedi]

SWIM is on 30mg Methadone and 30mg Paroxetine. He has been advised to go back onto Venlafaxine (Effexor), in order to better combat his depression.
However, from what he has read Paroxetine almost definately has a potentiating effect on methadone, whereas he has been unable to find out how Venlafaxine would effect his Methadone. Knowing that Ven is not a typical SSRI, he has now started to worry it may decrease the potency of his Methadone, which in any case, he feels is at too low a dosage.
Is he worrying unecessarily, or is he doing the wrong thing in terms of his MMT? Any info or experiences, gratefully accepted.