Have a deposit in my hands for my old Lincoln PT 185 and am looking for more power. I am trying to decide between the PowerMaster 256 and the PowerTig 250ex. Is the ONLY difference that the PowerMaster does not have the scratch start ability?

I will be working with 1/4 6061 aluminum building trailers and need as much power as i can to keep this stuff hot.

Anyone with either of these machines doing 1/4 aluminum??

Thanks!!