Dave - as has been mentioned, there has been some misinformation here and there. The DLE 20 is very sensitive to low end mixture settings, and it affects the slow down, but the high end lean-ness seems to affect it more. ahicks helped me understand that the high end being slightly lean can mean it's a little 'hot' when pulling back to idle like for approach, and that has been my experience with this particular engine.
There *WAS* an ignition with a "step" built in to the curve which created nightmares for many. Others may chime in with exact knowledge of which version that it. If yours is 2 years old, it likely could have that module - if I were you, I'd call Tom and ValleyView and talk it out with him. He is very helpful, and not one prone to BS his customers.

My DLE 20 is a sweetheart NOW after getting a couple hours run time on it, and making sure the high end is not overly-lean....yours will be the same. It's a great engine.