Thank you for the replies, I would be more than happy with tacho charging as I personally think I am a mechanically minded pilot and always take care of the engine, whether that be airborne or taxying. I agree that brakes to brakes is open to being abused by some and as such the owner fits the bill which isn't fair but I certainly never did that before. Generally I'd always round up to the nearest 5 mins so if anything the owner was getting a good deal and I assumed that how most would do it. This Hobbs malarkey I feel is unfair, I am not pilot in command (for logbook purposes) of the aircraft for example when I stick the master on as park of my walk around so why should I fit the bill as the Hobbs merrily ticks over.
Any way I'm having a bit of a rant here, I've just done a type conversion on another aircraft which is known for having a slow Hobbs, you win some you lose some I suppose.
Cheers