I was thinking about this question a lot, due to the current topic that floats through the forum and i think i got to a completely different view of it. Basically cyber- and bioware influences your spiritual balance through lowering your essence. For me (and according to the RAW) essence is a vague description of what we would call soul or at least something that keeps your soul grounded to your body. If you put a lot of "unnatural" stuff in your body, the only thing you do, is shrinking your inner flame of life, from a camp-fire to a close-to-the-edge-cigarette-lighter flame. Mana (and especially mana-based-magic) influences exactly this part of your entity. So in my opinion, the less essence you have, the easier is it to blow this little flame out.

Now the argument will come up, that healing magic acts controversly to this opinion, but actually it is quite the other way round. Though your heavy cybering, you lowered your life-power. And the less life power you have left, the more difficult it is to keep it going. Therefore you get penalties to cast healing magic on a cybered character, not because the cyber hinders the magic, but because of your low essence. The spell says only, that you have to subtract your lost essence from the dice-pool, but if you would have no cyber at all, just losing essence e.g. through drugs etc, this modifier should work nevertheless. You see?

This side of view seems (IMHO) more attached to the canon and it even doesn´t afflict the basic rules that technique is the natural enemy of magic (and theoretically the other way round) because you don´t want to influence the technique, but the human around it.^^

I hope i made clear what i wanted to say. Discussing in other languages than your mother-tongue, is quite borderline-esque.^^

I agree with you to a point. I agree with your analogy about low essence and why you shouldn't be more magical resistant the lower your essence is (and thus Cybermance give mages bonuses to try and kill you magically). If you grant mundanes magic resistance I would say it would be equal to half their essence rating (round down) (to denote their vague knowledge of magical theory and magical defence). In the case of Cybermancines, I would take their negative essence as a bonus to the caster to hit them. IIRC in past editions of SR, Cyberzombies were dual natured and also astral beacons (not the person but the magic keeping the person alive was the beacon). I need to go over the Cybermancine rules for SR4 but I would almost go as far to say that a mage could attack the magic trapping a Cyberzombie's soul and effectively kill them instantly (due to releasing their soul to a better place). That being said the speed and effectiveness of most Cyberzombies would make doing this hard at best. And you can bet that most Cyberzombie's will hire at least basic magic protection.

I don´t have the rules in mind, but is the magic that keeps cyberzombies alive, not the metatechnique of quickening and always "protected" by the additional invest of karma to make it harder to dispell?