You don't get down to the track too much do you? I have seen the 07 zx6r out run zx10 on the track. Yeah they r modded up and if you figure everything you have into the 6 you could have just got the 10. But the 10 for me 2008 looks kinda shitty and the zx6r looks really cool. Besides some guys don't have the extra cash to pay up front for a stock zx10 but can get the 6 and add as the go. If you think that the 10 is running lower 9's stock then your wrong. Upper 9's or lower 10's more likely maybe but here is a link. with both slips on 6r and a 10 together and see how close they run the 1/4I like the white, it looks very clean.
And as for the swing arm, you have a 600... Why? Just put the extra money into a 10 instead of the exhaust/ swing arm and you'll go faster in a straight easily. A 10 can run a quarter mile in the low 9s bone stock. What's the 6 gonne do even with the mods?