Most of Tim Nash's flash advantages are going to be felt on the street as opposed to at the track. Not only does his flash eliminate the top speed limiter on our Gen II's, but much more (and often) noticeable is how utterly smooth the bike will handle at lower rpms. Significantly less engine braking as is so often commented on by new Gen II buyers. More mid-range torque.
When we bought both Shala & my 09's, they had already been modded somewhat, in that the CAT's were removed and both bikes had Power Commander V's installed to correct fueling, and they both had Big Air kits installed. My bike was dyno tuned to match, supposedly by a pro, and all I could think about at set speeds, was how utterly annoying the bike was as it constantly surged as if hunting for something. Couldn't find a speed or RPM range between 2500 and 5000 that didn't surge. The good folks at Dyno Jet finally sent me a new PCV, and that took like 75-80 % of the surge out of it, but shortly after I went ahead and sent Tim my ECU for a flash. HOWLYMOLY, no comparison. My bike feels like it should have to begin with. But I have never rode a Gen II that was completely OEM to compare it to.
I'd say that the Nash Flash will be the best money you can feed the mod monkey, and especially true if you plan on dumping your CAT or doing any aftermarket pipe swaps etc. Besides, if you don't do the Flash, be prepared to hear the limiter kick in just when your hwy ride becomes exciting - right around 135 mph.