Folks,
For my two bob's worth, the Comanche 400 achieved a small increase in TAS for a very large increase in fuel flow, compare to a -260C, otherwise much the same as any Comanche 250/260.
I remember our -260C (first one in Australia- delivered across the pacific by a QF Captain who had not flown anything with less than four engines since his Lincoln conversion in the RAAF) with great affection, pity it got written of in Standard GA Accident Scenario No. 3
The 400, a good example of "hull speed" where the increase in the rate of knots is marginal, despite the extra HP.
Tootle pip!!
PS: If you are going to fly any of them, tight control of IAS on approach is essential to achieving something approximating the book landing field length (including factoring) ---- no carrying 10 kts for Mum and the kids.