For information I have run some test using the blitz cable and the provided software. Config Atari 1040STF + external drive connected with a blitz cable.
As a short summary I was not very successful!
In order to test the solution I have used a program from DrT (a syhthesizer editor) with a copy protection that resists to all "standard" copy programs.
I have decompressed the archive from [ProTos] and from the archive found @ "Build the Blitz Turbo cable, the super floppy copier!"
The copy process failed for all the programs with the exception of blitz2/b_turbo.prg and blitz3/faster2.prg, using the default parameters, which is obviously not a really good score!
But even worse I decided to retry the programs that succeeded the first time and this time they all failed!!! I then tested a third time and "faster2.prg" was the only one to work? I have also played with the parameters (speed, number of tracks, etc) without success!
This indicates that the blitz cable does not provide a reliable solution in my context? This is may be due to my drives (documentations mention that speed of drives must match closely?) or may be due to the protection mechanism used by DrT soft (I believe the protection is based on so called data "under the index hole") ... The copy protection is somewhat partially (and unfortunately marginaly) reproduced on the copy as instead of geting the "bombs" the program hangs in most of the cases.
To finish on a positive note I have heard from the vendor that he was successful in copying a lot of games (and he is also suppose to send me a diskette with the prog he was using)!!!