The inspiration for Tweed Drive has been 50's tube amps with their soft, rich sound that has set the standard for guitar sound for over half a century.
Tweed Drive has a transparent, dynamic and soft overdrive that seems to be missing from most multichannel amps. Tweed drive is very sensitive to the type of guitar used. The greater the output in guitar microphones, the more edge you get from the drive, and vice versa. Boost-feature allows you for example to enhance your solos. In practice this feature does the same as cranking up the volume on your Tweed amp. Getting more overdrive allows you to shift from rhythm playing to blues lead sounds.
Tweed Drive is designed to be a stand alone effect, but I see no harm in boosting amplifier with it. Adjusting Boost and Gain controls you can even get a fully clean boost.