I don't think we need to discuss this any more, because we clearly have different opinions about what cyberlimbs entail. As I see it, the core (heh) difference in our views is that I see a cybertorso and a skull as a shell rather than a limb, and that these won't be involved, and this next bit is the important part, from a game mechanics standpoint. You believe that they will.
We've clearly exhausted our arugments, as we're now just going back and forth over real world examples, which have little to no impact on the rules. You say torsos and skulls are limbs and should be included when considering average or weakest limb, I don't. There, that pretty much sums it up. Until we get official clarification, I'll refrain from discussing this with you any more.
Noble Drake; I am indeed oversimplifying the process, because I feel that the game mechanics do not account for real world examples.
While I agree that in your example, 80lbs bags of powder is going to be heavily wearing on your back if you carry it stretched out in front of you or over your shoulder, I also feel like futuristic cybernetic replacements could have the potential to alleviate this action by carrying the bag neatly tucked underneath the arm, close to the body. Since we don't know how these futuristic limbs are connected to the frame of the person using them, this whole argument becomes kind of moot.
Again, from a game mechanics point of view I don't see the torso as being that involved; if that is indeed the case from a design standpoint, cyberlimbs just became a horribly inefficient way of upping your strength, which I think is a shame because cyberlimbs, along with cyber eyes, are such a staple of the setting to me.
To put the previous example in context, if the torso is indeed counted as a limb for the purposes of tests (whatever the nature), the costs raise significantly.
In total, a STR and AGI 3 suite of two arms, two legs, and a torso would cost at least 80k nuyen and 5.5 essence. The same as alpha would be 96k nuyen and 4.4 essence.
Due to the added essence cost, it would no longer be possible to do this with Used grade 'ware.
Each attribute rating point (STR and AGI individually) above 3 would cost 25k nuyen (5k*5) for standard and 30k (6k*5) for alpha, up to (presumably) racial maximum.
In total, a STR and AGI 6 suite of two arms, two legs, and a torso would total at least 230k nuyen and 5.5 essence. The same as alpha would be 276k nuyen and 4.4 essence.
Each enhancement point above racial max would cost 32.5k (6.5k*5) nuyen for standard and 39k (6.5k*5*1.2) for alpha, up to racial max plus three.
In total, a STR and AGI 9 suite of two arms, two legs, and a torso would total 405k nuyen, and 5.5 essence. The same as alpha would be 486k nuyen, and 4.4 essence.
Tell me, if this is how the rules are intended to work, when would anyone ever use these items? The essence and nuyen cost is so prohibitively high that it completely negates the usefulness of these mods, as enhancing strength through muscle replacement or muscle augmentation/toner is cheaper in all respects except karma spent on attributes. It's borderline with four limbs, but adding a requirement for the torso pushes it over the edge in terms of cost effectiveness.
[EDIT]
The above also seems to be directly contradicting the intention of the writers;
"On the other hand, [cyberlimbs] are cheap and easy to service and upgrade, so in the end they became even more popular for the less fortunate."
Cyberlimbs always were the poor man's choice, but the way it's being interpreted from a game mechanics standpoint chummers might as well get full muscle replacements to up their strength AND agility, because it ends up being cheaper at only 25k per attribute point.
Jack Dockworker can get full cybernetic replacements to become stronger (by one attribute point) for 105k (80k for limbs, 25k for STR+1 customization), or he could just get muscle replacements R1 for 25k. Wait, what?
Personal opinion (and I'm obviously biased, if that wasn't abundantly clear by now); cyberlimbs got royally screwed in the new rules, and doesn't follow the spirit (or intention) of the setting at all.