Thankyou everyone - some very helpful responses & very informative.
Genghis the Engineer - you are quite correct, I was (incorrectly) referring to my Tacho Time counter as a "Hobbs Meter" which I now know is an entirely different item.
(Neither of my aircraft are fitted with Hobbs meters - both just have the integral Tacho Time counters, both display to 2 decimal places are mechanically driven fitted to Continental C90s).
"Wrench1" - In the interest of keeping things as simple as possible (and as both aircraft are privately owned so no syndicate aircraft time / charging complications) - I will continue to log all times as per "Wristwatch" times - so "keeping it "Old School" as you say.
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.
Much appreciated for all the replies. Thanks again !