Thanks for that, Guppy. It is clear and helpful.
Even though the theory makes sense, no other engine I operate (from turbo charged 450 hp, through normal aspirated IO540 etc down to 60hp Rotax) loses so much rpm on final at normal speed. 1100 rpm still seems too slow, with manifold showing 15 inches and airspeed 60. I would be concerned if it was a normal engine, and nothing you have written makes me feel better about that.
The book for the airplane does not say anything about what to expect either. My mechanic says there are no rpm adjustments except for takeoff power, and it is good at that setting, showing 2400. Once the throttle is pulled back though, the prop goes straight to the fine pitch stop.
Has anyone flown one of these airplanes who can reassure me?