The Fort save wasn't as popular because Undead are immune to them (and therefore Heal doesn't hurt them).
Will save for half, like the Inflict line, seemed to be the most popular. Instead of half, many people had it save for 1d6/level (max 15d6) or something like that.
There were also discussions about letting Negative Energy Protection stop Harm (it currently doesn't), tagging it an (Evil) spell, or just flat out limiting its damage to 100 points (no save, but can't reduce you below 1d4 HP)