We've started looking at this and I tried adding into my Clojure Lein project.clj
[cascalog/cascalog-core "3.0.0" :exclusion [[cascading/cascading-hadoop]]]
I ran two equivalent jobs one with the above and the other with just [cascalog/cascalog-core "3.0.0"] and they both took the same length of time.
Is this similar to what you tried?
I used 2.5.3 as I believe that's what Cascalog is using by default.
Although I've now realised I'm also including cascading.avro/avro-scheme 2.5.0 which is pulling in cascading/cascading-hadoop 2.5.5 having now looked at the output of "lein deps :tree" :( I'll run another test but was curious what people thought of what I've tried so far.