First off- Congrats! I haven't ridden the long version, but I have ridden standard Lightnings and I've got over 21k miles on my '04 Firebolt. These bikes rock!
As for racing- the bikes can't ride themselves. Outside of racing in a straight line, the only way anyone outruns anyone else is by out-riding them. If your buddy can ride better than you he's going to eat your lunch whether you're on an EX500 or an R1. On the other hand, your XB12 is easier to ride than his R6. You've got a much more usable powerband with way more low end power stuffed into a more stable chassis. His bike makes more peak power, but he has to rev to over 10k rpm to get it. This should allow you to out power him coming off of corners and get a better exit speed.
As for racing- the bikes can't ride themselves. Outside of racing in a straight line, the only way anyone outruns anyone else is by out-riding them. If your buddy can ride better than you he's going to eat your lunch whether you're on an EX500 or an R1. On the other hand, your XB12 is easier to ride than his R6. You've got a much more usable powerband with way more low end power stuffed into a more stable chassis. His bike makes more peak power, but he has to rev to over 10k rpm to get it. This should allow you to out power him coming off of corners and get a better exit speed.