Snowmobiles have put exhaust valves to good use for years, when it comes to engine "innovation" everything has already been done or tried before. The only difference is now technology advance in materials, manufacturing,analysis and electronic control capability have made these ideas possible to implement.
Although possible to develope performance enhancing features, applications such model aircraft given weight and size constraints, make it impractical to utilize.If you are looking for state of the art two strokes, look at outboard motors and snowmobiles.
Jennings and other authors have noted that their concepts would be easier to apply if computers were available at the time.The time area principles laid out by Jennings are valid today.Using a computer program makes time area calculations easy, several companies market software that perform these functions.

If you are looking for more in depth and "modern" material on the subject look up Gordon Blairs book "The Design and Simulation of Two Stroke Engines"

There hasn't been much published on the subject of two stroke engines in recent years except about emission reduction strategies.