I've had the re-flash done. The only other mod is a Delkivic can, which makes very little difference other than looking and sounding better, and saving 14 lbs of weight over the stock muffler.
The low-end (2K to 4K) power is definitely better, but if you are looking for a gigantic difference, you'll be disappointed. Yes, it pulls harder at those low revs, but not OhMyGoshMyArmsArePullingOutOfTheirSockets harder. It's like going from an 1200cc bike to a 1400cc bike. Above 5K, I'm not sure if there is any difference at all according to my butt-dyno.
Exactly what Racer Boy said except my can is a Leo Vince Titanium. I'm satisfied with the reflash, there is a difference, but not a huge difference. Before the reflash I could barely feel the difference between the regular map and the economy map. After the reflash I could really feel the difference. The eco map is unchanged and the regular map is the Guhl map.
Another similar to what Racer Boy said.... I have a stock exhaust and stock muffler. The difference after the reflash is quite apparent (and appreciated) from the RPM areas I (and most people) tend to ride- the 2 to 6K RPM area. Not much difference after that. It isn't going to transform the bike into something it is not, but make it feel like it should have to start with. Installation is super easy although a bit pricey for what it is. If you want more performance, it will require replacing the exhaust system and putting in a PC which is a lot more time and $.