I've switched all my Phals to Sphagnum. Since then I've had much better success with my Phals. I use the best quality moss I can find. I have almost no dead roots and change the moss annually. My moss never drys out. I grow outdoors so my conditions are different than most, but I've very happy with my results.
I have been having trouble with my phals drying out, since it got cold. They are on humidity tray, but the relative humidity in the house this morning was 36%. I did not check the level for the plants. I have been adding more moss to my phals, which helps the bigger ones, but the smaller plants are dry in less than a week. I think the best solution, at least for me, would be a humidifier in the room
Last year at the beginning of summer I repotted a bunch of my phals in clear plastic pots with Better Gro Phalaenopsis Mix which is a fir bark, charcoal and perlite mixture. I kid you not they are krazy with roots and it's only been seven months. The rest I potted up in sphag with clay pots. They are doing pretty well too but for my growing conditions but so far I think the bark mix is the winner. It's harder to know with the clay pots what the roots look like though.