Our Maine Cat has both, min-keels for general off the wind sailing, beaching, etc. Then a single retractable dagger (port hull), (weights about 75lbs) which drops from 2ft draft to 5ft draft. I thought about removing it to save weight, but after sailing 2000 miles, I can say it helps quite a bit. The boat points probably about 7 deg higher with the board. I agree that its easier to drop down off the wind and go a bit quicker, but for us, when the wind is up, we don't lose that much speed... It also helps alleviate weatherhelm.
I've heard of people removing the mini keels from the Maine Cat but not the daggerboard.