I also like the Seneca I, and as recently as last week I once again toyed with the idea of the possibility of improving the OEI performance of a Seneca I by installing flap/aileron gap seals, main wheel fairings, flap track fairings, wing to fuselage fairings, Powerflow exhaust system, etc. I still occasionally review the possibility of using a smaller twin for this purpose. When all is said and done, the Ho makes the most sense.
Coincidentally, I came across a Beechcraft BE-58 Baron operating cost survey, an airplane of similar size to the N/A Navajo. Flown 150 hrs. per year, the hourly operating cost comes in at $317. Flown more, that rate will further decrease. That's not bad for a six seat twin.