Crank Advice

ive got road cranks on my bike at the mo. working out pretty well.
@hippy: never seen a road crank snap. told by reliable sources - cavendish cycles etc. - that the dura ace road cranks (7703 i think?) are likely to snap/crack when put under the continued pressure of riding on the street, skidding and braking with ur feet. yes the track cranks are hollow too, but they must be made differently???

I would remove those shops from your list of reliable sources then!. Unless they have lab tests to prove it, it just sounds like they are making it up as they go along to me.
What is possibly more likely to snap is a cheap set of cranks that are poorly made, rather than the highest quality Shimano produce.