I can't even imagine the amount of extra exponential dps this staff is going to offer. Everyone else is like "yay an extra cast of damage," but the difference is we scale exponentially from haste because we need to get lunar and solar enegy faster to proc our mastery. So, gaining extra spells is the same deal. With our new 4 piece and the staff plus the haste on it. we'll be in a 65-70% extra damage mastery pretty much every few casts. It will be ridiculous. Not only are we the highest scaling spec and class for haste but the proc does even more.
Unlike other classes that actually have abilities that they would say something like "damn I wish it didn't proc on that" balance druids benefit from any extra spell cast. Example say it proced on a shamans flame shock I would be ok and a small damage increase like for everyone else. But if it procced a druids dot we would get more starsurge procs, basically doing the same thing as the staff. Or if it procced on a wrath starfire or starsurge itself it would just make us doing more % damage on top of the extra damage.
This would happen EVERY proc, not just someone hoping it would happen on a chance of a chance to proc like some other classes talking about perfect scenarios.