Now GBTimelapse can capture High Dynamic Range time-lapse images in addition to its other powerful features.
Using its AutoRamp feature, GBTimelapse captures a set of three images at each step (at a normal exposure, at two stops under exposed and at two stops over exposed. You can capture RAW or JPG and save to your computer or to your camera (for faster operation).
And it can do this while controlling a motion control dolly!
Please watch this demo video and take a look at the sample HDR time-lapse. It produced an amazing "Holy Grail" result even with a Canon T3i capturing JPGs.