Gotta say that if you are looking at buying a bike as an investment, well I wouldn't bother with the FZS600. Simply too many of them about. Also great bike that it is, is it really a bike that people will drool over in years to come?
Who knew, 25 years ago, that restored FS1E's would be selling for £5000 and Z1's for £20,000 nowadays?.
Rough, early, pedal equipped Fizzy's were offered for around £200 then. Now they are like The Holy Grail.
If we had known what was to happen we would have all been buying them up for the next to nothing and stashing them away.
It's very difficult to predict which bikes will be regarded as desirable/collectable in years to come.