I've done the cutting up method before, especially internally it works quite well. drilled and fixed an expanding bolt lifting eye into each piece to lift them out. Very clean, minimal mess and quick too.
For once I am in agreement with Doobin and Gazcro, for the kind of work you do Routy, its not going to damage your machine as you wont use it long enough and at £50 extra for getting your pecker out

, even for 10 mins, its good value for the customer and worth owning for you. Wacker plates, disc cutters and cat and gennys are also good ways of topping up the rate for the smaller owner op out there. Or in my case, justifying a higher rate than the competition. Very little overhead for a better return.
If the job needs all day hammering then you can come up with a rate to suit, or hire in if you are really worried about it. Machines are pretty tough and providing you keep up the greasing you wont do too much damage to the machine. Theres more damage to be done by using the pecker as a leaver or running it when its not engaged with anything. Used properly they are a great tool even on micro diggers and far better than being stood over a beaver pack!