SWIM has posted similar threads before, so apoligies if he sounds like a broken record. He's enquired about using ethnos/herbals while on methadone, without much response.
In this case, he is interested in the semi-legal spectrum of drugs available, principally RC's (or "legals" which contain them as their main ingredient), as well as GBL/GHB which he has still never tried. He knows that the latter is a depressant like methadone, so is expecting some cautionary words on that front. Having said that SWIM can quite easily combine his methadone with similar drugs such as benzos or carisoprodal.
Any advice would be very much appreciated as SWIM has no idea really as to how others on MMT would fit in stimulating RC's like methylone or mephedrone.