break in is very important according to the miller tech with 30 years experience at being a tech for miller. if you dont want to pay the money, you can do it with a length of grid fencing or an old mattress spring section. just follow the instructions on how much time at each amperage increment and it will work out fine. however when you spend that much on a machine having a professional break it in for a 100 bucks seems worth it.
just my opinion
darren

I would definately put some good  load on her in the first few hours. I have a yr 2000  model that burns 1 1/2 to 2 liters oil every 200 hrs, may be because I did'nt work it hard enough, although I didn't let it idle much during the first 50-60 hrs. Running at a constant rpm does'nt help with seating the rings I've heard.  The machine just turned over 4900 hrs on the hr meter. Only things ( other than regular maint. ) I've done is change the water pump and a voltage sensor on the 110 volt circuit. It has saved me a bundle on fuel.  Have a good day - WS