Dyno Tune? Not really necessary, but $97 isn't a bad price. I have the same bike as you, and put a dynojet stage 1 kit ($100) in my bike to go along with a full titanium muzzy exhaust. All paid for by the guy who hit me.
Anyway, I did the install myself. Only took me about 4 hours, and I know the work was done right. So the $379 estimate sounds about right for $90/hour labor. If you know how to take the carberators out as a unit and remove the float bowl, you can do this mod yourself. Don't worry about syncing the carbs, as you won't be touching this area at all. I have a manometer, but never even bothered to hook it up. I set the c-clip on the new needles to the recommended position (there were 4 to choose from) and the bike runs great. Dynojet claims you will get power gains across the entire rpm range.
I can't really say I noticed an appreciable power gain, but the sound of the new exhaust is awesome! I never had power problems to begin with though so I'm still incredibly happy. So to answer your question, in my opinion I didn't notice $500 worth of extra power, but mine sort of came free of charge. The new look and sound of the exhaust system were worth more to me than the power gain.
BTW, if you buy a dynojet ket, it comes with a certificate for a free dyno run. And no, I never bothered to get mine dynoed.