I did grow the big strap-leaved Vandas in true hydroponics - flood and drain for a while, very successfully in terms of how well they grew ; from memory, more than 50% double spiked, and I got great flower counts too. But no compost would stay in the pots, it all got flushed away, and the roots grew into a tangle and went right across the tank - and I don't means those stringy grey hanging roots you see on plants newly imported from Bangkok, I mean ones up to a cm thick growing straight out sideways and branching everywhere. So the only way I could take a plant to a show was by starting out with a pair of bolt cutters or very strong secateurs, and cutting the plant out from the jungle - which of course was a major set-back when it came back.
I have been pondering how to solve that one for years ( of course I gave it up after only one year) and maybe have the answer - I just need to find a few square feet of bench free, to set it up and try again.
Btw I used to measure the growth rate by measuring how many inches of new leaf growth I got each month - the best were growing more than 10 inches - which amounts to several pairs of leaves a year.on each plant . I have some pictures , but neither time nor space to put them up here.