I have always thought hiring on tacho hours also looked after the engine. If it was me I would talk to my LAME to get the best idea on charging to instill the best practice. My old aeroclub regularly hired out at tacho hours. You didn't mind flying at 23/24 when it was logging you more hours than you pay for whilst still getting a reasonable TAS. Nowdays its all on hobbs as soon as its turning its burning your wallet. Gets the urge to get into the air in a hurry, incentive to taxi faster and also make the best avail taxiway exit to get you back to apron in a hurry...tacho removes all that
