Coco products!?!? NOOOOOOOOO!!!!!!!
I'm sure you've heard they can have lots of salts in them, so you have to wash them really well blah blah blah, but they also break down VERY quickly and are intolerant of fertilizers (unless you regularly flush pots). Coco products have a tendency to look normal on top, but to turn to sludge underneath. Therefore, you don't know when you need to repot to avoid the sludge suffocating your roots. Unless you just loveeeee to repot everything every couple months, I'd stay away.
My highland/intermediate mix? The prepotted phal mix you can buy at Lowes. That's my secret. I pour it from the bag, into the pot. Lawlz.
Its perlite, charcoal, fir bark...maybe something else? Very free draining, but actually holds some water, even though you wouldn't expect it to.
I've also used pure fir bark, pure cedar chips/mulch, MESQUITE, etc. You could probably grow neps in Gak if you wanted to...or broken glass, or on a brick...they're really not that picky.