Tuning by ear isn't a great way to set up an engine for optimum operation. First and foremost, you cannot always hear detonation (ping). This can cause damage as minor as a cracked spark plug to as major as broken pistons and bent valves - and you can't always hear it hapening. Secondly, todays gasolines are seldom consistant in antiknock (octane) compounds from one truck load to another and can be a deterrant to good mileage, detonation reduction and overall performance. A timing light and vacuum gauge along with known tuning specs are your best tools for good overall performance.
And yes, I do tune by ear, but only as my starting point for my light and gauge.