Should I read at lower speeds?

[IceBreaker]

That .sys file only deals with the ATIP issue, Blindwrite does NOT have built-in active emulators (weak sector emulation, physical media info, Laserlock emulation, pregap emulation, etc...)

So your backup really IS 1:1, and if it works in your burner it is not only because the .sys file hides the ATIP, but also because the original pregap of the CD-ROM was successfully copied by BW.
To confirm this, you can uninstall Blindwrite and launch the game after inserting your backup in a reader (not burner, cf. ATIP!) that can read pregap (ie. recent Liteon DVD-readers?), so that the game can check for pregap: you will see that with the BW-made backup, the game will still work, even though the BW .sys file is absent...