I tried the DC upgrade today. No explosion, no fires, nothing melted and no magic smoke released.
Using DCEN (DC Electrode Negative) at the 95A setting I'm geting less spatter than before and it appares to work fine. My added parts did not even get warm.
However at the 35A setting (still DCEN) I got a lot of spatter (more than with AC) and I had problems avoiding burning holes in 0.9mm steel. I also tried 35A with DCEP (DC Electrode positive) and it appared to work better with the thin steel, less burn troughs and less spatter.