Most books advocate DME over LME for quality and stability. Years ago, I swapped to pale DME in 50lb. bulk packs, preferring its keeping qualities and lighter starting color in use (you can use additional grains steeped in a grain bag to attain any desired final color) and in bulk it costs a lot less per lb. Stored LME darkens over time quite quickly and attain a bit of a licorice taste. In contrast, I have kept DME for a year and it's not noticably altered.
To convert recipes, know that the ratio of LME to DME is 1.25:1, or in reverse the ratio of DME to LME is 0.8:1. Hence multiply any LME amounts by 0.8 to get the amount of DME to substitute.
Stir well off heat when first adding to make sure none sticks to the kettle bottom and you'll be fine! Clumps will dissolve in 5-10 minutes.