Whilst looking to see if I had any notes about Firebird tape stream loaders, I found an Exile deprotector I'd written a few years ago. With a little bit of tweaking I got it to work with the version at Acornpreservation.org

http://www.acornpreservation.org/archiv ... l%2040-80T)/Exile%20(Superior)%20(B)%20(Disc)%20(Dual%2040-80T)%20%5BFDI%5D.zip

I guess it shows that once the spade work is done, to bypass the protection is quite simple...
Seems like it's a different version to that in the archives, since the files are different lengths + execute addresses. Unfortunately, since B-Em doesn't seem to allow me to save files to disk, I can't test if it works

10*LOAD !BOOT

[Breaks loop]
20?&1F28=&60

[Create loop in BASIC]
30REPEAT
40CALL&1F10

[Sidestep self EORing loop]
50IF ?&1F13=&28 THEN ?&1F28=&C9:?&1F2A=&60
60IF ?&1F13=&29 THEN ?&1F28=&60:?&1F2A=&D0
70UNTIL ?&1F13=0

[Change JMP&7800 to JMP&1B00]
80?&1FDC=&4C : ?&1FDD=0 : ?&1FDE=&1B
90P%=&1B00

[Change CH (of CH."!B") to LO
100[LDA#&4C : STA&789B : LDA#&4F : STA&789C: JMP&7800
110]

[Continue as normal]
120CALL&1F2C

This will drop you to the BASIC prompt with !B loaded.
Typing 120 will delete 120 which performs *RUN EXILEL.
RUNning the program will load EXILE (the picture) and sort out the video.

Next, all that is required is a memory editor to view the "virtual" catalogue information at E00 (filenames) and F00 (file information).

There's a custom filesystem in place, so files can only be *LOADed and *SAVEd, *COPY won't work!

Erm, what's stopping it? I can save to disc absolutely fine. Unless you're doing something daft like saving to an FDI.

I can save to disc without any problems... but then I replace disc 0/2 with the FDI, load another file off it, return to my other disc where I'd previously saved the file (EXILE.SSD) and it's not got the file I'd just saved on it.
The file's date modified hasn't altered either.
I've tried using Model B and Model B+ 1770.
Loading any disc in Drive 1/3 gives me an empty disc with 00 files of 31 on 00 tracks.

Just found the problem. A quick workaround seems to be to either quit the emulator after writing to disc (somewhat impractical) or to run the emulator fullscreen.