Digital flash design

[Greg Beetham]

I think the design compromise we ended up with could have been handled better than it was, with it's preflash metering.
I havn't had any lazyeye people subjects myself, but others have had and still have a nightmare with it.
I have had problems with birds who are easly startled, some are so alert (honeyeaters) that, because of the preflash, I have quite a few shots where the subject birds wings are in blurry motion, (I consider it mandatory too use daylight flash fill -1/3rd or 2/3rds to kill the dark shadows created by the bright sun here in the tropics) Strangely enough some birds don't even seem to notice or care (parrots).
Granted the designers had to come up with something too overcome the reflectance difference problem between the surface of the CCD sensor and film, and still be retroactively compatible with the last generation of film cameras.
My question is, why couldn't they create a recess in the body field stop, (say the bottom hemisphere) the rear wall of which being covered by a layer of something with the same properties as film? Then the TTL sensor could meter directly off it instead.
Any calibration difference issues (recess not being as deep as the sensor plane for example, due to the AS/SSS mechanism, and the metering zone being located on the edge of the image field etc.) could have been handled "in house" by the camera surely.
Anyone have any thoughts?
Greg