I rode my RS250 NX5 back to back with my MC21 Track Bike this year, the MC21 has RVF400 forks. The RVF forks are in dire need of a full strip & rebuild so it wasn't really a fair comparison, but for the record they felt terrible compared to the NX5 forks.

The RVF forks are going to be revalved / resprung/ rebushed by Reactive Suspension in Jan, so I'll let you know how they compare against the NX5 after the first track day.

But if I was just running a NSR (and not 2 RS250's as well) I would have definitely sourced a pair of USD NF5, NX5 or NXA forks as a first choice for (or if) replacing the SE / SP original forks.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30