Man I'm glad I read this. I use both of these a lot and still debate it from time to time. Roger completely nailed my findings with the 1272. That said, I like it better. It leaves more body and ends slighly less dry. The slick, almost oily, mouthfeel is nice too. You can use far less crystal/dextrine/adjuncts and still get a nice full bodied mouthfeel. I think the 1056 is too dry sometimes. If your beer is all hops then its a good choice. I would easily use 1056 for a double IPA but for an apa, amber, or even a malty IPA I like 1272.
my personal experience is that if you are going to use munich in an american beer, the 1272 is a must. With 1056 so much of the earthy character is lost.
I'm trying US-56 right now and it doesn't seem to flocculate nearly as well as 1272. I don't remember having as much of a problem with the 1056.
Happiness is a homebrewed pale ale and a bolivar belicoso fino.