Well at the end of the day, all the anecdotes and dummy tests pertaining to something this tiny don't mean anything (the DPS difference is < 0.5%, in favour of the spellstone at that, but anyway), when various different spreadsheets happen to overwhelmingly line up on one side of the issue. Spellstone is just objectively better, and I even listed a number of valid reasons why in all likelihood it's actually even better than spreadsheets predict it to be. While alternate points of view when presented cogently are conducive to discussion, the mathematical reality of things can't be denied here. If, for some reason, Firestones are really performing better than Spellstones currently then that'd mostly likely be the result of a bug of some kind. I don't think there's much else to add on the subject of stones so I'll just end with that.
Imp damage right now is much more in line with what it should be, yeah. I think a guildy said they saw their Imp's Firebolts go down like 25-30% in damage compared to what it was before the Demonic Knowledge fix, so I'd hope that'd be enough for the Felguard to at least finally edge out ahead. Or maybe not quite yet.