We were playing with the ideas of several grades or models fo cyberlimbs. Initially two grades were discussed which were Basic Prosthetic Cyberlimbs and Advanced Cyberlimbs.
Basic Prosthetics are cheap. made for the everyday joe that may need a limb due to tragedy and whatnot but doesn't have the cash for a top of the line model. I eyeballed these at like 5-7k for an arm and 7-10k for a leg. They have no or virtually no ECU and have all proprietary parts mass prodiced so they are not modifiable. They come set to whatever the user's natural str and qui is up to Racial Maximum or nearly so, but not higher. They are not meant for performance. They could be obvious or for 500 or so you can buy a sleeve for it that makes makes it synthetic. No reason for multiple versions since they aren't made for customizability.
Advanced Prosthetics are the cyberlimbs we see in the game now. These limbs can be set to the user's str and qui levels my a doctor, and can handle up to Racial Modified Limits without much of a problem. They have ECU depending on whether they are designed to be obvious or stealthy.
Now, here's where my rules vary.
I think performance cyberlimbs should be able to be adjusted to high levels of performance but there should be tradeoffs. I think that higher levels of qui and str should be purchased and should be priced on a sliding scale so the higher the stat the higher the cost.
I think that it should not inherintly cost essence for the capability to move faster or be stonger, but you should have the option to reinforce the interface between the limb and the body but it shouldn't be automatic. I think the limb should automatically operate at the owner's stats (or level he is reinforced to) unless the owner makes a conscious choice to override the built in safeties.
I think that when the user makes the conscious decision to override the safeties that the limb should perform to the specs that he purchased it up to, but when doing so it should cause the user damage. High speed causes high inertia and can stress the anchoring points if not reinforced enough. High strength can cause the anchoring points to stress and rip. The only activity I dont think should apply at a penalty is pure grip, like crushing a beer can, something independant what so ever from the mounting points.
I think the user should suffer damage on a sliding scale proportional to the amount of str or qui over his own natural attribute that he used. For example something like a power equal to the number of points exceeded and a wound level determined by that also, like starting at light it goes up a wound level for each 2 or three points exceeded. This gives the nifty visualization of someone ripping their shoulder off at the chance to do something heroic.

Ideas? Suggestions? I'd liek to refine this based on people's input.