I have used Carafa for Porters before and no other roasts. I've even used it for oatmeal stouts. It's all personal. I have decided that Carafa is not for me. The flavor is just....well.....weird to me. Doesn't suit my palate I guess. Think of a dunkel without the yeast notes.
When I see a dark beer, I want a little bite of roasted barley or a chocolate malt flavor - I am not really a fan of blackened IPA's for this reason, too. If you want to smoothe it out, how about coffee malt and chocolate malts? If you want it dark you could add a bit of black patent for color adjustment.
Just my $0.02.
Being Dealt (kegged): Carbed Crystal light lemonade for the boys, Delta Bravo IPA, Applewinder
Primary: Climbing stout
Primary #2: ESB
Big Blind: Pucker Bitter
Tasty Remembrances: White 'N Nerdy, Dynamite Red (Hop bursted), APA, The Bonaduce (irish Red), runners stout, ridgeback brown,
from my big ass computer sitting on my floor