Fur's balance macro suggests two macro's.
One for IS/MF/Wrath.
One for IS/MF/Starfire.

With only one druid, its pretty easy to switch when you notice a proc.

My druids are messing around with an Eclipse InnerSpace solution.
Basically three keymaps per druid.
Keymaps 1 & 2, both use 1 as the hotkey, and either call the IS/MF/W or the IS/MF/SF macro's.
Keymap 3 is a two-step toggle, enabling one and disabling the other.
Then an addon like MSBT announces which druid has the proc, but the announcement is not Eclipse but rather G7 (or G8-G11).
When it announces G9, I press G9, which is the hotkey for the 3rd druids toggle macro.

If you did not want to bother with switching macro's, in another thread Fur suggested going with:
/castsequence Wrath, Wrath, Wrath, Starfire, Starfire, Starfire, Starfire
As the 3rd line in the macro.
That way, you at least get some of the benefits of Eclipse on each proc.