Not exactly a trivial task... Incanter uses several sizable Java libraries (such as Parallel Colt) under the hood, so a port would first need to either finding suitable replacements or re-writing that code as well.

Definitely not a trivial task--though it may be a worthy task. Incanter has moved from PColt to JBlas, and is moving toward core.matrix which will abstract the linear algebra stuff. If anything, I'd guess that Racket might be an easier ask than Clojure due to the JVM weirdness around boxing / unboxing of numbers passed to and from the underlying jblas (it's entirely possible I don't understand what I'm talking about re boxing / unboxing, though I've heard tell that the JVM makes some aspects of numerical work very challenging).