Sdiver68 would be the guy to ask about performance. He has a post with his dyno graph and comments.
An ECU flash allows you to tune more. Woolich has made a name for themselves over the past few years. Of course it depends on your tuner and his/her level of detail and knowledge. As for raw numbers, I dont think any tune is going to make huge power gains over stock with mods. However, where that power is made and how smooth its delivered is what translates into better performance. Throttle response and engine braking can be fine tuned as well. A load bearing dyno is the best way to tune any wheel driven application combined with data logging on the street.
The only Woolich tuner near me is booked 3 months out. I'm thinking about purchasing the Woolich package with the log box. I can have them or someone send me a map and flash it to the ECU. From there I can do my own data logging and tinker till my hearts content. Then I can get it on a dyno and go from there. The entire package is $895. Seriously considering it as a new hobby.
Simply put, the best way to tune a motorcycle is an ECU flash with dyno time to build a map. Should cost less than $500.