I'd go away from a sanity system tied to limb replacement unless folks are going to go into the realm of actual augmentation, then that can be used to balance cost but I've never been a huge fan of it.
"steamware" should have some huge social stigma with it unless its commonplace to see folks with modifications. I'd say the other major drawback would be the unpredictability of the devices of the day or with that setting. Most of that is custom and prototype work so it has bugs or require constant adjustment to keep it working. Alot of that can be played in downtime but something can be used to handle critical failures.
Just thinking off the cuff while on lunch.
The sanity loss would be tied to losing the limb, not getting a replacement - most likely Post Traumatic Stress Disorder (Soldier's Heart, Shell Shock, etc.) In other words Stress Damage.
Recovery would neither be hindered nor aided by the replacement of the limb. This would be a modification of The Table of Ouch rather than a gear related rule.
Social stigma is a factor, if nothing else having 'steamware' subtracts from any attempts to Blend. People remember folks with prosthetics. People with oversized mechanical claws tend to stand out in the crowd for some reason....
My current means of handling 'bugs' is to have a roll when stressing the device, if a 1 (or sometimes a 1 or 2) is rolled then it may be activated as a critical failure in much the same way as weapons malfunctions.
At best, barring Gadget picks, prosthetics allow a trade off, loss of two points Dex for one point of Str (allowing for a stronger grip, not whole body strength). That kind of thing.
Mind you, in the current group no one has lost a limb... yet. (Actually, this group is a lot more cerebral than expected - genteel investigators rather than hard boiled detectives and spies.)
The Auld Grump
*EDIT* One possible result of Stress Damage from the loss of a limb is addiction - at a time when cocaine and morphine could be purchased over the counter, but aspirin required a prescription....