That's all fine and dandy, but you also have to consider the maintenance cost of StFl, which is 15 AsP per cast (every 24ish seconds), which is also a global you're not gaining AsP (anywhere from 8 to 15 AsP) but rather losing it (15 AsP), and you're also giving up Incarnation for it. You can't just say "SOTF+StFl makes Starfall best on ST" without considering the other option. Like yeah,
if you take StFl, I'm sure Starfall would be better on ST, but is that option better than taking Inc and doing the usual? That's the important distinction unless you're dead set in going StFl, which many of us are not. I'm personally not a fan of a DoT AsP Spender that's very inconvenient to use.
This requires a lot more math that I'm sure @
Slippykins will probably do assuming this Soul ring goes through as is.