I use an early Boyer on my 850. It probably has a fixed advance curve, but if you are looking for performance, programmable advance curves are probably a good way to go. There are about 4 variables in getting your tuning right. fuel type, comp. ratio, jetting, inlet port size and the shape of the ignition advance curve. I my case, I use methanol fuel, standard compression ratio, supposedly fixed advance. 30mm inlet ports. I vary the size of the needle jest and the shape of the needle to get the mid-range jetting right.
So in effect, all but two of the variables are fixed. If you have a programmable advance curve, you can adjust the ignition advance in a much more flexible way.
If I was not so lazy, I would buy a modern Boyer and work with it. However methanol fuel hides-up your tuning errors. So I would probably only get real value from a programmable ignition system, if I wanted to race using petrol as fuel. For a street bike, a fixed ignition curve is probably better. The closer you get your tuning to ideal, the more weather dependent it probably becomes.