It’s been a long time since I’ve seen a Fischer damper, but my memory is they are very similar. If if was building anything that was turning less than 8500 I’d use nothing but the IW or a FD. Both designs have a much broader damping range, and both become less effective at RPM higher than that. If you are up that high in RPM then you’d want some sort of elastomeric damper. Good look getting one tuned for your application though.