Hi Capt W E Johns
Seems to me that the TIO-540 needs a lot of inches and a lot of gas for not many extra horses... I fly a Lycoming IO-540 which is benched at over 300 BHP with around 28" and 2700 RPM, using about 100 LPH.
Probably to some degree that is quite right but the main advantage is the T engine will continue putting out that power for many thousands of feet in an upwards direction. Basically the turbo charged engine will work as though it is at sea level up to around 20,000ft. Obviously somethin' no N/A engine will ever achieve!
regards
1M