Hi, It sounds like you have your miltonia and miltoniopsis mixed up.
Miltonias are not as showy as miltoniopsis, but grow like weeds in
warm climates (I'm in east central Florida). I cannot grow
miltoniopsis without a lot of moving around as they do not like too
much heat--I've spent a lot of money on them & eventually lost every
one. Won't have one on the place anymore. Miltonias on the other hand
will go from a 4" pot to an 8" pot in just a few years. I have a bunch
of Miltonia Adelante that have to be repotted often as they grow so
fast. Now to the Vuylstekearas--you said the plants were ratty looking
from the start?? Could be that you just bought bad plants?? If you
started with bad plants (& who knows what's wrong with them) they are
hard to bring back. All Oncidiinae like to be pot bound in a well
drained mix but don't want to dry out!
The rule in breeding is a cool grower crossed with a warm grower will
most likely be a warm grower. We have Vuyl. Aloha Passion that does
fine for us. It's a Mary Cavanaugh hybrid. Back to
Miltonia/Miltoniopsis---lots of growers tag their plants Milt. so &
so--Milt. is proper both for Miltonia & Miltoniopsis. Best way to tell
is: miltoniopsis foliage is usually very light green & the flowers are
"Pansy like" Miltonias are not nearly as showy--but are very heat
tolorant. Hope this helps, Bill