I just got a GT-1, and I'm using Yosemite 10.10.5. I experience most of the probs Synthetica described. I am able to create a custom LiveSet by dragging and dropping. Copy doesn't work, nor does Paste. The only way I've found to get a single patch from computer to GT is to make a LiveSet, put it in the set, and apply the set. As Synthetica describes, the LiveSet always inserts starting at patch #1 on the GT.
I don't see any of these as big problems, but wanted to share my experience for the sake of comparison.
It'd be great if Copy and Paste worked, because that's way healthier for my hands than dragging and dropping, but it's not a huge bummer.