I've found that it has less to do with the string and more to do with the racquet. I've been stringing a bunch of poly in my racquets of late and have had no arm issues. But my racquet is soft, 59-62 stiffness.
When I used PDGTs, it didn't matter if it was poly or multi -- I had arm issues either way.
So I suggest looking up the stiffness of your racquet. If its a stiff racquet, then any poly is probably not right for you regardless if it's the "softest" poly out there.