I don't think there's any "muddying" things up by looking at a specific bike and saying there's no direct comparison especially between a FZ1 and FJ-09. Suspensions are usually pretty specific. Rear linkages are pretty specific as is swing arm length, wheelbase, ...front suspensions are even more finicky. Overall the front and rear have to be balanced, not only in how they are sprung, but how they are damped as well...
One easy way to get a feeling is to call someone who actually knows suspension and getting a recommendation. I would call Traxxion Dynamics ...tell them real numbers, weight, passenger weight, gear weight, luggage and give them a description how you ride (mostly trackdays, touring, agressive sport-touring) and they can get pretty spot for front springs and rear spring on your bike's fork/shock combo.
In my experience (well over 100+K miles on the track and street--work on my own bike but I am no professional suspension mechanic) it pays to not guess too much and let those who study, sell, fix, maintian and upgrade suspensions give me a good starting point...I tweak things from there. The times I've got in trouble and muddied the waters is where I took a WAG from the get go...based on a pure guess. YMMV and you're welcome to "try" it. Who knows you could get lucky by assuming the suspension of a FZ1 is darned close to the FJ-09...but maybe not. Best of luck. Keep the rubber side down.
Matt
