pipehead,
Yes, Also, a few years back, I welded on a County building near Yellowstone Park. They too wanted Hobart blah, blah wire: I had Lincoln 232 spooled up and ready to go. I asked they said no, I bought Hobart, worked everyday for 3 weeks, went night skiing every evening at Snow King. OK, the skiing hurt a bit for the first couple of days....
Oh, back to the point. They told me the Hobart had been qualified for their Lo-temp Charpy's and Seismic requirements. Teton County ROCKS!! (see discovery channel Super Volcanos) Sometimes, it can just be a contractors familiarity and success with a particular product.
At least, you have some name brand fillers to work with, and not required to use some Hung Chow's 0U812 crud.
Worst case scenario is you will learn the finer operating characteristics of a new wire.
"They always just said spec was 5p or lo-hi and you could run your pref..... " There is a case of a specific filler (5P being a Lincoln trademark) being called out!
good luck to ya,
John