QUOTE (wind_in_the_stones @ Feb 10 2010, 08:21 PM)

What justification is there for having a penalty? It makes it to difficult for the mage (or magic) to determine what state to restore to?
Oh, that'd be a nice glitch result - your boxes are healed, but your body rejects your left cyber arm. Roll Body against infection.
Well, if you're asking RAW...
QUOTE (SR4A pg 207)
Healing Characters with Implants: Low-Essence characters are
more difficult to heal, as implants (or other damage) disrupt the body’s
holistic integrity. In game terms, this means a dice pool modifier applies
to the Spellcasting Test equal to the subject’s lost Essence (rounded
down). So trying to heal a character with Essence 4 (2 Essence
points of implants) incurs a –2 dice pool modifier.
...as for me, personally? I like to make every decision a player makes about a character important. It's like foreshadowing in a movie - if a character mentions they can 'fix anything with tires', then it's a safe bet that they'll have to prove it at some point in the film. If a character is low-essence, I like to play up the fact that they're a walking death machine, but they're also only barely alive/human. Mages flinch, animals get creeped out, Healing magic sputters...you are become Deathbot, Destroyer of Heavy Response Teams, and all it cost you was %95 of your soul. Any opportunity I can find to remind the player that their character is unique and his decisions are important makes the character a little more developed. I'm not looking for leverage here, just flavor.
You do make an interesting point about cyborgs having a strange biology. I had always played it as an aura deficiency, but that could be interesting as well. Thanks!