Not a bad design at all for a pan-european model either.
You could have a 16A and 25A version where the 16 fits the 25 but not visa versa.
I don't think fusing plugs down to suit an applience is a bad idea either. Although I hate the British approach which is both bulky and bypassable (fusing 13 amps on things that should use 3amps etc)
I'd suggest a small slot in keyed cartridge fuse.
Small plugs for small loads would only need tiny 3 amp fuses anyway, something along the lines of those used in cars.
Larger appliences could have physically bigger plugs that carrier larger (potentially hotter) fuse cartridges.
These should be non-interchangable making it impossible to over-fuse an applience.
Just make sure it's incompatable with NEMA
Use the keying on the socket to ensure polarity that way you don't comprimise the pins strength/capacity to carry current by making one larger than the other etc.
