Your post implies that it is sufficient to take IFF (but not cast it) to get the buff? I didn't realize someone finally went through the pain to confirm this.....
Bullocks did some testing, where he had a very low (about 3.5% on paper doll) crit rate. Over a few hundred casts, with no feral FF, his actual crit rate was in the 3-5% range. With FFF on the target, but only 300 casts, he saw a crit rate of almost 9%.
That is few enough casts that a false positive was a real possibility (any statisticians want to figure the odds?). Until we see a more thorough test, I'm inclined to believe his results (and the wording on the tooltip).World of Warcraft - English (NA) Forums -> Improved FF is indeed affected by Feral FF
Also, Starfall is borderline effective in a single-target rotation (may have higher DPET than a non-eclipse Starfire, particularly at low +spellpower). If you want to model it:
A single target, at range, will be hit by 10 stars (should be 12 with Starfall Glyph at 80). The stars have a 2% spellpower coefficient, each. Starfall is affected by Nature's Majesty, Vengeance, and Moonglow. In 3.02, Starfall crits cause Moonkin mana regen, but Blue has said that will be nerfed. Base damage for each star is
Enemies near the moonkin (tooltip says "within five yards of the enemy target", but that is not the observed behavior) take some additional damage, but as a general rule Moonkin won't want to be in melee range of bosses. Coefficient for these stars is 0.5% (each). Damage is
70: 45 <-- Edited
I'm not sure if this matters in the Simulationcraft context, but Starfall is treated as a buff on the Druid, not as a DoT. This means that changes in the Druid's state can affect affect future stars. For instance, if the Druid dies, Starfall goes away. If the Druid gains (or loses) Owlkin Frenzy, the damage of future stars goes up (or down).