I'm playing with G25 which was design for younger games than Enthusia and it works. There's no clutch on pedal and I can't change gears with shifter but every buttons works and 900 degrees rotation too (with wheel gear levers) so I think that it will work.
You can easily patch a switch in from the shifter unit to the clutch pedal to give you a digital clutch. Throw an on/off switch into the run of wire and you can easily enable/disable it for legacy games like enthusia.
As for messing around with the physics, the thing which always impressed me the most was found when drifting (particularly the cobra) on the big square of tarmac. Not only can you let go of the wheel and maintain the drift perfectly with just the throttle, but without touching the wheel you can also change direction and hold a counter-drift or stop the drift entirely and drive off.
Of course, i've only tried all of that with the G25. I can't remember if my DFP could spin quickly enough to do all of that hands-free. Certainly the DFGT could do it.