I've just levelled up from Silver to Gold. MAN, I wish I hadn't. Just lost 16 straight games in Season Mode, and get pummelled each time. Why did I do it?? I was going along at about .700 in season mode, and since levelling up have been below .100
I did it because I had basically maxed out all of the team I wanted to keep and had boosted all the boosters. But god, Gold is hard. Wishing I hadn't bothered. I enjoyed it at Silver. I hate it at Gold.
If you're considering it, my suggestion would be don't!