What do you hope to achieve?
Most "regular" FIīs are qualified to instruct in both-simlators and aircraft....plus there is hardly any training in simulators (that is not already covered by "regular" instructors) outside of IR-training or type rating training....
I believe SFI is a position for someone who has lost his medical, or canīt fly a "real" aircraft for another reason....but doubt there are a lot of jobs out there for one...