It depends on the LED and the transformer. I've found that most MR-16 retrofits and a few of the integrated fixtures work fine with the Litetech but almost all of the SCB, bi-pin, etc. do not. You just need to try the combination you want together, and let them run for hours. Sometimes they'll work OK initially and then start strobing or flickering after a while.
Or, you can use the small Hatch magnetic transformers and not worry about it.