Brake disc myth or not?

I have a guy at work that reckons whenever you change your pads you need to machine your discs at the same time otherwise you will chew out your pads alot faster.
 
True or False?
 

Also anyone try EBC 'yellow stuff' brake pads?

New pads won't make any difference, though it is true that regular machining can help with brake wear.
Due to heat effects, parts of the disc can become harder than normal. The surrounding areas will wear away quicker, so you get a disc face that is no longer flat. This will only get worse if not machined, until you can get significant vibrations when using the brakes and you'll chew through the pads quicker.
Its what a lot of people blame on 'warped discs'.

Its not necessary to machine rotors but a good idea and dose not cost a lot. That's if they are still above the minimum thickness
 
If you but new rotors on defiantly use new pads

Old rotors are fine as long as they're in good nick. It's a good idea to rub them down with some sandpaper before installing new pads. Removes the old pad transfer layer so you're back to bare metal for the new pads and scuffs up any shine or glazing you might have.

Ebc yellows are good. Had them on the front for almost a year now and still heaps of meat left. In that time I've done more than 5 track days and the pads have always been good. No fade even after 5 laps or more and they work great even when cold. Feel just like any other pad. Once warm they stop even better. Pretty dusty though so if you wont track them then ebc reds would probably be better.