Tuning wise, I say dyno and on road tuning both is the best method to tune.
On the dyno, you can tune the higher rpm ranges, because you can hold a specific RPM at a certain gear for a longer period of time, and experiment with various fuel ratio and ignition for maximum power possible.
On road tuning, can tune lower end. Usually doing on road will reveal mapping holes that cannot be seen on dyno, due to different loads present on real life situations. Some parts of the map are not used when on the dyno, so are extrapolated (calculated/guessed). When on the road, the extreme ranges of the map, usually on the corners, are used, unlike on the dyno, which only uses a specific range of cells.
So for me, although I do tune on the road, I'd still get the car strapped on the dyno for peak power tuning.