When I do extract batches, I tend to use liquid. Seems to be easier to use (no clumping, getting DME over everything, etc). My trick is to do the following:
Steep specialty grains as the brew water heats up.
When it gets to about 150ish, back the flame down
Get another stock pot and pour some of the hot liquor into it, add your LME to soften/mix
By the time you've mixed all your LME and cleaned out the container, your specialty grains are about done, so pull em out and rinse a bit.
Add the LME to the main kettle and kick that flame up
Whenever I tried using DME, I would just get a clumpy disaster. That being said, I do keep DME on hand at all times to adjust pre-boil gravity, make starters, use in bread, etc