Hicks, once again I agree with you regarding the #4 ignition ..... if the user understands what is going on and can live with it. One good friend of mine has an older DLE20 on a SIG CUB. This elderly man is very intelligent and a retired aerospace engineer but no matter how I tried to explain the #4 ignition to him ..... I just don't think he ever fully understood what I was trying to explain. The engine is good as long as someone else sets the needles and throttle curve. And (usually during landing) as long as the throttle is either all the way down to idle or just above the step point it is OK. But touch that throttle and the RPM's jump up in a way that startles him every time.
I'm the kind of guy who couldn't tolerate that sort of thing and would replace that ignition in a heartbeat! But that's just me!