Bill, I have used Hydroton and many other LECA (Light weight Expanded Clay Aggregates). They can be used with bark like pumice, lava rock or charcoal. At the greenhouse at my University, all orchids are planted in the bark, LECA mixture including Phals, Paphiopedilums, Cattleyas etc. But I personally do not like to mix them up. The reasons for it being that bark or any organic media will eventually decompose and then it will be labour and water intensive and also difficult to segregate and reuse the LECA which can be used for ever (Original Hydroton is very very costly in India roughly 15 dollars per litre, other LECA brands cost 5 dollars a Litre, but I still do not like to waste it anyways.) It finally boils down to what is convenient for you and your growing conditions. Here in Bremen, I have all my Cattleyas planted in 100% LECA, just that you have to water more often as it will dry out pretty fast.