Good day, same (debatable) human here that wants ask about the upgrade rules for Cyberlimbs.
The Havens upgrade rules are already pretty generous - so I can't flaw them in that aspects - however I think some of the upgrade rules around cyberlimbs don't make too much sense. By RAW - an upgraded cyberlimb is a complete purchase of a new limb, with whatever therapy and procedure it would take to install the limb. In the Haven, to my delight, this is not the case - you only pay the price difference. So, yes, big happy here.
The issue I have, is unlike a Gun or Piece of armor, limbs get expensive - fast - 100k is not a far fetch for a limb - currently my rather empty limbs are valued between 70k and 110k, upgrading to bulk modifications or customized agility/strength are cheaper to be bought as a addon to a completely new limb, than to be interchanged with an existing limb - which I feel doesn't make that much sense. Once a runner gets to Delta Grade for instance, it would be cheaper using the upgrade rules to get a betaware limb to later get another delta grade limb, that it would be to upgrade a deltagrade limb - which I feel makes little, if any sense.
When it comes to armors or weapons, while they can be pricy - and in the nature upgrade rulings, while buying a YNT softweave is essentially getting a new set of "fabric" for the armor, making it a new item. Upgrading from a Unused-Standard limb by default is a entirely new limb. Now obviously, I am not going to argue we should make it that upgrading a limb means a complete resell, though given the nature of the current rules as they are - I am going to argue at least for Beta/Delta ware grades - that upgrading items such as bulk/custom (or other avail increasing customs) should be treated as a cost difference with a check on total limb availability.
For lower grades, I can understand, though specifically for Beta ware (since you would require a prime run for delta) or Delta ware (since it can't be upgraded), I would say it's fair that if an exception is to be made, it would be made for these grades given the difficulty/cost to upgrade.