I do not know what the cost difference would be to produce a ram 500 sized turbine compared to a P-80 sized turbine. The ones that are starting to come on the the market and their prices, service and dependability will most likely tell the story.
Wouldn't the smaller turbine allow for a lower cost turbine aircraft package, such as airframe, gear, hardware etc. It might even allow for more of a variety of airframes also, with less production costs of the airframe, hardware and gear.
The goal being to have more affordable turbine aircraft to bring in the new pilots. They can always move to the more expensive kits when their ready or just continue to have fun with the more affordable ones..
Paul