I use EC/HC on most details where I need heavy correction. Via PC I actually prefer HC because it is easier to work (EC takes forever to break down properly), and leaves less hazing; but of course the cut is less. HC has a lot more cut than OC imo; similar to OHC. EC has more than both.
As for what is bad about them - they bog down pads very easily, and they rarely finish down clean enough to go to LSP, but that is to be expected with heavy cutting compounds. Remember to swap pads a lot.