Young action with SD15 and 70-200
I do not shoot with a Sigma camera, but, in these photos, there is no sky so not much danger of burning out highlights. Anyway, I would take such advise with a grain of salt and always check my images to make sure such advise is warranted. By underexposing images, no matter how desirable for certain reasons, you run the risk of losing color vitality. If you are shooting RAW, you can recover the lost ev easily. If not, why not? With my Nikon cam, if I shoot RAW, I have a lot more leeway before I lose highlights.