I've never had HIDs before my Civ Sport, but having just returned from clocking up quite a few miles driving 'with enthusiasm' around mountain roads in the Highlands and Isle of Skye, I can only say they are a definite improvement over halogens - much clearer definition of detail allowing a more relaxed driving style as your eyes don't have to search so hard for potential problems ahead (suicidal deer can make a mess of your Civic!
).
I'm not sure that there's a tremendous advantage in more normal urban/motorway driving though.....