Well, you answered it in your post...
"create optimal ignition characteristic"
Yeah, you can fuel it, but you'll be able to change the ignition timing.
So, the question becomes...
Do you have the availability of a really good dyno, most aren't because they really can't product accurate, repeatable runs...?
And do you have a knowledgeable tuner?
Generally most aren't. Hard enough to get the fuel right, let alone get the ignition right. Most dyno operators are "certified" because they bought the dyno and went to a short school. It's a tool to make money..."I've got more HP than you"...well, HP doesn't always win races...if it did, Rossi would have lost because he was down on HP and top speed.
Last year, we used the 46i Fuel Injection Module. Less than $200, and I can use it at the track. Dyno tuned at http://4and6.com
and then I could change three settings with a screw driver, just like jets, but it takes almost no time at all. No lap top necessary.
I do know of one person that used the Kit Yamaha box. But he has a dyno at his house, and he's been responsible for his own bikes for some time.