I just started growing a few months ago, after being absent for a few years, and the semi-hydro method was perfect for my arrangements. Some are doing better than others, and those that at first disliked the new medium, are turning the corner and doing really well.
I can't say that I am very good about the timing of moving the orchids to semi-hydro. Since I was getting a lot of plants bare root, or in older medium, I plunged in with everything, and as you can see, some took over a month to get back on board.
The BC is doing phenomenal, like 5 new shoots, and root growth up the wazoo. The two phals respectively took 2 weeks and a month to "convert" they suffered for a while, but now are sending new leaves and roots and are on the right track, doing much better.
The Masdavellia (sp?) shed about half it's leaves, but it too took about 2 weeks, and is sending up new shoots and roots at a quick pace.
Humidity and temp is roughly 75% and 75degrees a bit moister and warmer in the day, and cooler and dryer at night. Probably not dry enough, but it's still warm relatively in NYC, so when the temps and humidity drop, I'm sure I'll be in the sweet spot.
I was watering every 2-3 days, which was too much, now I water every 4-5 days depending on the water level.
I have 4 ascocendas which really did not do well in semi-hydro at all. I've converted them to the glass vase setup, and drain and fill once a day, and they seem to be doing much better now. Vandas + semi-hydro just did not work for me, maybe if I watered much much less frequently, but they need to have their roots dry out, and the leca just didn't let that happen.
One thing I was suprised, is how moist the leca really keeps the roots, I wouldn't be suprised if regular plants did fine in leca.
Pretty much all of the plants are regenerating new root systems, I want to stress that if people considering it, the previous root structure is totally not compatible with semi-hydro. This is just my experience, but most of the older root systems are rotting away, and the plants are regenerating new roots. Even if they are growing fine leaves as my paphs are, they are all regenerating new root systems, and the older roots do not look that healthy. I probably over watered at the start, but now I'm realizing less is more, especially in my situation where it's always >65% humidity (mainly for the vandaceous types).