Done and do both.
Dyno positives:
- safe
- warm (at the moment)
- power runs
- easy to see current cells in the map to enable changes
Dyno negatives:
- articificial environment
- cooling is always an issue to replicate airflow that you would normally see on the road
- more expensive (add dyno time of about £75 per hour)
- always need checking on the road too
I believe that road mapping gives the best useable results as it is mapped in the environment that the car is usually driven. But there is the issue of road safety. There shouldn't be any reason to go silly speeds on the road to map so rule that out it just gets a bit difficult to map cars above 400bhp on the road as you run out of road too quickly. Things like a std overtake is difficult to replicate on the dyno so all cars mapped on the dyno need checking and fine tuned on the road aswell.
Mine is mostly mapped on the road with fine tuning on the dyno.
Dynos are nice and warm though - a big plus in this weather
fyi - I have use of a dyno in Norwich.