you can't beat dyno tuning. dyno's are useful in making adjustment from stock to modified. you can see the results of every mod you do.
on one of my race bike, I bought a stock 1993 zx7 with a dip in the midrange. a full pipe and jet kit (several runs and adjustments) removed the dip and increase hp all around. the pipe length was adjusted, needle height, jet sizes, and different filters.
on another race bike, we tested the difference with newly ported intakes and roughed up exhaust.
putting different bikes on the same dyno will show accurate results. every race team i've competed with uses a dyno.