This is going to depend pretty heavily on your build(s) and the levels at which you're playing. There is some general, anecdotal advice I can give beyond the obvious "things do less damage" math (
link)
"Offspec" or "bonus" self-heals are less useful
Some examples are Ravager and Frenzied Berserker T5s, Spellsinger's Sustaining Song (except at absolute endgame), Artificer Admixtures (I can't speak to the RMM T5). Self-healing is nerfed to 40% in R1 and an additional 4% per skull. In my experience, this boils down to "you have to make a concerted effort to heal yourself" - cure / repair / negative energy spells will do the job, but you might have to pause between combats. For what it's worth, this largely isn't an issue in Epics because Rejuv Cocoon or Renewal are readily available options