If you are really concerned about dynamic range at low ISO, get hold of an Eos film body and a roll of Velvia 50 or Pan 50 to use with your existing lenses. I have been pleased with Pan 50, which I use regularly in my OM-10, and have a roll in an Eos 5 at the moment.
Otherwise, as others have said, the dynamic range is less than at higher ISO settings, but may be more than enough for the photo you are taking. If not, there is always HDR, which can be better done with good judgement in post, than anything the camera may offer. The main time I have been frustrated with a lack of DR is when including a bright sky in the frame, and not being able to get correct exposure on both the subject and the sky.
Edit: reading back to the original post, I wouldn't worry about the DR comments for action photos, unless you want a stunning sky in the background.