I was thinking it would be difficult with the reliance on old textures. If it's an easy process than you won't have any arguments from me, I love UDIM. I only know UDIM from scratch though, as in mapping something with numbered tile use and painting textures to go with those UVs. And never more than 2 tiles at most. But moving forward no more stacked for me.

Change it NOW! Lol. But seriously, I wouldn't suggest you change her mapping if I wasn't sure it was an easy process. According to ADP it is ;)