There's an old question - is the red that I see the same as the red that you see? - something that is probably unknowable.

I imagine we'd still see the same range of colours, except they'd be assigned to a much greater range of frequencies - i.e. what appears to be red, is actually far infra-red with pretty much all of the traditional "visual" spectrum appearing blue/violet.

Or it might all be random..., in any case I'd expect the brain to adapt to the new inputs well enough:

http://www.wired.com/wired/archive/15.04/esp.html

Intuitively, this makes sense - being able to recover data from an overwritten part of the hard drive effectively means the capacity has been multiplied (if you can recover from 1 overwrite, while still being able to get the new data, the capacity has just doubled.)

If this was easy enough to do, Seagate, Hitachi, WD etc. would all be doing it (or are already).

That said, taking the word of someone whose job is actually recovering data - well, that might not be a good idea.

"But: do the measurement in your own world. My software, hardware and artificial measured usage pattern may differ from yours, subtly but enough that my conclusion doesn't transfer. Be scientific about it :)"

Best advice I've seen - try and build up a representative sample of a day's work (or just a random sample if that's not easily determinable), copy it, run one copy on unencrypted disks and one on the mandated encryption.

If there's a significant difference take the evidence to your IT dept. or supervisor and hope for a favourable decision.