ne of the best experiences I've had in Australia (I am Brazilian) was to go to the 8 day retreat in Byron Yoga Centre. I've read here that some people said they "use" teachers that are still being trained.. Just to clarify, when I was there, there was just 1 class per day like this (at 6am), and you could choose to have another one, just one hour later, with a trained teacher. So it's up to you.
My experience was excellent, I would love to do it again. Everybody there is really lovely, classes were amazing, the place is amazing. Thank you everybody for this incredible experience, I learned a lot with you :)