I've used this mix for Phals and paphs with pretty good success...it works very well as long as you are careful about not watering too often. Also..since it already contains fertillizer, there is no need to fertillize the plants for a few months after repotting.
Heed the warnings as well as the advice to add perlite. This mix is mostly intended for terrestrials as has been stated, and for that purpose it can be fine. Paphs and phrags and some seedlngs love it. The biggest problem for most mature orchids is the early breakdown, lack of aeration and tendency to hold water too long. Conversely, once it dries out, it is difficult to re-wet.