Could we please have an option to convert from 340/440 to turboprop, as happened in real world?
I'd like this as well very much, but there's an issue: the advantage of the 540 through 5800 would reside in higher speeds compared to the piston ones. However, in the game, a family of aircraft's speed is dictated by its slower model. Thus, all prop variants would be slow, and as a result, not really interesting.
We'd need a full design change in order to make these viable.