| Just my two peneth,
I had a ride on a 620 that whilst was very well put together, was not super trick at the end of oct last year at mallory in the cold and got down into the 1:01's in three sessions, i'd done 1:02.97 on my 583 when we raced there at the first round. Really didn't feel any different in the places you could open the throttle on it, and it turned and stopped far better than my 583 did.
I do think that its in the mind as the difference in power is pretty much negligable, its not like the difference between a 600 and a 1000 jap four.
Jimbers really has got on well with the 583 though so far, couldn't believe it was the same person after watching him at anglesey! | 
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