Kinkos-printed copy of SR4 firmly in hand, I spent last evening helping my group whip up characters for a campaign I'll be running as soon as everyone works out their schedules. Unfortunately, we ran into a number of different pesky problems in chargen.

First, how do you do math for averaging cyberlimb attributes? One of the players wants to play a mostly-full-conversion character (he fell in love with the new capacity rules), and he'll probably begin gameplay with 4 cyberlimbs and upgrade to the torso as soon as he can afford it. Now, I run into a problem with averaging his Body for damage resistance purposes. He has two cyberarms, Body 6, and two cyberlegs, Body 6. Either way I average, he'll get five Body against damage, but I'm trying to figure out, mathematically, exactly how it's supposed to work? Do you average his cyberlimb body ratings with his own? Do you do it based on loccation (four limbs, torso, and skull, averaging the bodies of each)? Is there some other bizarre method?

On a related note, how does cyberlimb armor work? Does it average with the rest of the characters body, or do you just sum the armor ratings the character bought? The latter makes more sense, since armor seems to be based on coverage as well as protection, but it also seems really powerful - far too powerful, in fact.

Third - is there an availability modifier for cyberware grades? I'd assume their would be, but I haven't been able to find anything either browsing the PDF or flipping through my hardcopy.

That "full borg" issue is a bit of thin ice still.

Basically if you have 4 limbs + torso (+ skull), there is no place left to have agility or strength, so there I would ignore the natural stats and only go for the cyber ones.
Downside: karma wont help you here, pal.

For body its a bit tougher. I would use cyber body for all "external" tests, while using the natural body for tests where its stated that cyberware wont help.
In theory you need to factor in natural body for the skull, too, as it will get replaced later I assume?
Drugs / Toxins / Disease come to mind as even a full borg still got some wetware that can be affected.

As there is no hit location system ingame, you average armor I guess, giving you not much room to get uber but still compete with the other cyberware.

Afaik there is no availability increase for cyberware, so no more "mystical" deltaware.

For cyberlimb attributes, the book has decided not to touch that can of worm and left the GM to decide how it should be.

You can either rule that only a certain limb is being used. Forexample, shooting a pistol might only involve 1 cyberarm; use that cyberarm's agility. With dual cyberarms, your character will no doubt prefer punch attacks, so you'd use cyberamr stats.

But, say he's climbing. That uses most of your body: average all stats available (legs, natural, arms).

Next comes special circumstances. Say the character is hanging from a building with 1 (cyver)arm, and a bad guy shoots his fingers. Use the cyberarm stats only, especially armour.

For general, non-descript actions, such as "I shoot at him", always average the stats, since the abstract nature of shooting at someone means he might hit his cyberarm, he might not.

Soo all of the above goes with armour, too. You don't add every point of armour purchased to his armour total, you average, unless it's a direct limb hit (pretty much GM descriptions as exampled above with the cliffhanging).

Technically there are 6 possible locations (2 arms, 2 legs, torso, head), but I think dividing by 5 instead is a bit more generous.