I would suspect that it's a 3000 with the microdrive replaced with a compact flash memory card of some sort.
I doubt it, it would be much cheaper for Sharp to fit 128Mb of NAND flash to the mobo and save on the CF connectors + also it would stop after sales market from retro fitting the HDD which I'm sure Sharp wouldn't want. If they used a CF card then they would still need some NAND flash for the initrd/zimage so you would probably see it specced as 192Mb storagre (or maybe not).... anyway I have feeling it's going to be traditional NAND type flash...
I think you misunderestimate the cost of connectors vs the cost of making substantially different devices, and that the Z isn't a very high volume/low margin product.
CF cards are *cheap* commodity devices*, so if the 3000 and 1000 are identical except for one is uDrive the other CF (and a different case cover), there's huge economies of scale in having them identical right up to the last second of deciding to fit an uDrive or a CF and picking the right colour of case.
* Ok, a 128MB card is, what, US$20? and connector US$1, and the flash chips alone would be ?$5, but then you've got to solder the flash and go through further testing, whereas the CF card could be programmed ready to go.
Localisation is also easier, just in case they do decide to offer an English version again.
It also makes it easier to repair when bricked, which I guess is perhaps the most common reason for repair - just swap or rewrite the CF.