I'm using both the firelands trinkets (Jaws, Eye) simply because of the int. As Disc I only go oom if I play stupidly (at least in current content, all normal modes and some FL heroics) so the int is worth more for me than spirit procs or no spirit procs. I do carry a Fall of Mortality and the Fiery Quitnessence in my bags in case it is needed though, which has mostly been when I for some reason spec Holy.
This is not to say it will be the same for everyone, but if the FL trinkets refuse to drop/mana is an issue, Tsunami is always a good backup choice since it has a solid amount of int and a nice spirit proc.