Lojban is not hard. If you have experience with formal language/predicate logic/programming it is trivial to modify that understanding.

How about having a conversation in it. (In normal conversations, people just don't have the time to engage in Type 2 processes -- most utterances take a few seconds at most. I've heard that lots of people tried to learn Lojban well enough to have real-time conversations in it and failed.) Also, the French, German, Russian, Spanish, or Portuguese you studied in high school are close enough to English -- not only genetically (all Indoeuropean languages, FWIW), but also typologically -- see http://en.wikipedia.org/wiki/Standard_Average_European. I've heard that native English speakers have an easier time learning French than Indonesian (probably the simplest non-creole natural language), FFS.