Good work.I am drinking my fourth all-grain brew and I must say it is my first brew that tastes like proper beer, I mean it resembles a beer style "English Porter". It has the body, it has the right amount of hops, not the colour though. I guess the Carafa grains should be in the mash for a bit longer. I think I am happy
A friend of mine who introduced me to home brewing, gave me a nice tip. He suggested that I should cool down the wort much more after boiling, I mean I only cooled it down to 24-25C, he said it was waaay to high, that is where the off-flavours came from. He said I should cool it down as low as possible for the yeast to kick off.
Most Ale yeasts work best between 18-21 deg C. Lower and the ferment is sluggish, above that and you can get "off" flavours.
If you want a darker colour without adding harsh coffee bitterness try Carafa Special III. Black as a very black thing but with only a hint of burnt toffee and coffee. Either mash it normally in with the usual grains or seperately steep it in warm water then add the resultant liquid to the boil.