Potting medium for dendrobium

[Lady Oscar]

I'm not sure exactly what my Den. suzukii x Den. tobaense is potted in, but it seems to involve some moss, and I've noticed it stays pretty moist for quite a while in my humid climate. Being paranoid now, I'm thinking of repotting it to check out the roots.

The medium I have right now is "Better-Gro Special Orchid Mix" (https://www.amazon.com/Sun-Bulb-5002.../dp/B005OK9KRK) which is fairly coarse. Would it be better to go with something finer? I'm concerned that this may drain _too_ well, since it sounds like this dendrobium wouldn't necessarily want to dry out completely. I'm also a bit concerned about support, since it's very tall compared to the pot diameter (and I haven't found a place to buy rhizome clips that doesn't have ridiculous shipping costs for Hawaii).

It's growing some new leaves out of the top of the tallest cane and has one newish aerial root, and one bloom left.