Ultimately - this will increase the engine time slightly more than "Tacho counter" time would, I am quite happy to carry out maintenance a few hours earlier than otherwise necessary.
I will continue to log the Engine time in the logbook as per Wristwatch times (so Engine on to Engine off) but will also note the Tacho Counter time after flight so future "Custodians" of the aircraft can have that figure also.... and then they can choose how they want to Log engine time going forward.
Why? When a tacho is unavailable it is quite reasonable to deduct 0.2 or 12 minutes as representing ground time and is certainly acceptable by the UK CAA.to be entered into the aircraft log books; unless the aircraft/ engine manufacturer stipulates otherwise.