As an update on this, I had mine done back in October/November. I've had a small amount of yellowing in one point on the screen again. Doesn't seem to be getting worse, so hopefully I'll be able to get it done again when I take it in to get the HW 3.0 upgrade (when it's available here).
Does anyone know if they're able to apply this to the smaller dash screen? I notice some yellowing there too, it's not as obvious, due to the darker colours, but it would be good to get that fixed too.