a huge difference,
the ikons are progressively wound, race tech springs are straight rate.
the question is what you want: if you just want to cruise, and not really ride it hard (like you Really mean it)or do a track day and you weigh between 135-210lbs. the ikons are ok if you run 5WT FORK OIL!!!
the race tech springs are if you really want it as good as you can get it, but you need to put emulators in along with 15wt-20wt fork oil. adding pre load adjusters is also a nice touch.
the progressive springs from a vstrom dl650 work very very well in the bonnie.
any spring for the sv-650 is correct for the bonnie, I ran sonic springs in mine and they were excellent and sonic has a wider range or spring rates.
if you let me know your wt. I can give you the correct rate for the track , or the street , I can also give you the correct drilling procedure for the damper tubes, thr rt inst. are incorrect.