Thanks - I will definitely wait on the Sharry Baby then - it's healthy as is anyway.
I was cleaning up my Epicat after I posted and found the reason it was going downhill - when it was last repotted into bark a fair bit of moss was left in the rootball - the plant was then watered as if it were in bark and when the pseudobulbs began to shrivel I guess watering was increased. Was happy to see that there were far more than just one healthy root. There's the one good one, a few that don't look great but aren't rotten and the new growth is actually putting out new roots, one a cm long, plus two barely started nubs (

). I cleaned all rotten roots and all the old moss out of the rootball, potted it into a tall SH container and have it in my terrarium under low light/high humidity/warm air where I hope it'll do well.