I have a Maxillaria variablis that needs a bit of help. Would a dendrobium mix be good? Seems like they like a lot of water, maybe add a bit of sphagnum?
I use loosely-packed sphagnum, usually in a plastic net pot, but have one in a clay pot, also with sphagnum that is doing very nicely. Small bark would work in a pot, too. These tend to ramble - new growths on top of older ones. Main thing, don't "clean up" sheaths between pseudobulbs - the roots run through there and trying to be "tidy" can kill the plant.