I'm pretty certain that they're both completely archival. I would've never thought otherwise; considering that it all comes down to the pigments and the paper.
I think gelatin & gum arabic are like Thelma & Louise.... they'll go out of this life together. . . .
I'm just not personally that interested in gum, solely for its look. I can appreciate a good gum print for sure, but it ain't really my bag.