Do a search for kinking black pastels and you'll see that even black pastel x black pastel (or black pastel X cinnamon) have the chance for severe genetic abnormalities/defects. Black pastels are not immune to any genetic problems as some people seem to think they are. Some people prefer a black pastel super to a cinnamon super as they say it results in a darker animal, but others prefer the cinnamon combos and supers. (I pick my cinnamons carefully, and prefer light cinnamons for light combos). As for whether it's worth the risk of a super, is up to you to decide. I've been struggling with the same issue, with my two Cin het pieds (My personal decision is to move away from the project and work on clown combos). Some people will consider you a monster of even considering it, and others will applaud a successful clutch if one happens.
Here are a couple threads I was able to dig up regarding super cin/Black pastel kinking/duckbilling, and I remember at least one other thread being posted within the last few months, that other people may be able to dig up -
http://ball-pythons.net/forums/showt...x-black-pastel
http://www.reptileradio.net/reptiler...p/t-38683.html