I'll be so bold and give you advise. Not that you need it, so it's more like my 2 cents. Go for the 600 class. It's were the natural progression leads you if you have the ambition to find out how good you are.
I'll still be racing in Derby-Phoenix's 750/twins class. It's not a highly competitive class, more like a gentlemen's class, which suits me because I don't have the ambition that WJB has. I know you do, John, don't deny it.
