I sold my road bike 2 weeks ago as I get just as good a work out on the mountain bike on the roads, without the speed I grant you, with the distinct advantage of being able to take to the XC routes part way 'round a route if I feel like it.
That's very useful as some of the local roads can get heavily congested and being able to simply revert to type and XC is a great tonic, taking me away from the smog and cars.
I find the road riding a tad boring if I'm honest – good for cadence work, but not very interesting!