Get David Vizard's book, "How to Build and Modify Chevrolet Small Block V-8 Camshafts and Valve Trains"
Commit it to memory and you will be just scratching the surface of camshaft design. Although there are cylinder head considerations, the dumb camshaft doesn't know if it's a Ford, Chevrolet or ?? V8, inline 6,etc.
To your original question:
Harvey Crane coined the term 'Hydraulic Intensity'. This is the difference between duration at .004" and at .050". The lower the number the higher the intensity. Those with a higher number will have lazy valve action and even though they have more off-seat valve time(ing) they are likely to produce less power over the entire operating range of the engine.
The area under the valve lift curve is much more important than the advertised duration. And as Panic and CNC-Dude pointed out, LSA will definitely change the characteristics of two cams with identical lobes.
