I'm no fan of the WBX, by far--I've been saying for at least a 15 years that
the factory should've put the Audi 2.3 fiver in there from the get-go.  But,
having said that, and acknowledging that I used to own a VW repair shop that
saw lots of head gasket-cases, I really have no real reservations about the
basic reliability of the WBX engine, itself.  The bottom-ends are
bullet-proof, and the heads can frequently go for well over 120k if treated
correctly.   Truth is, it's not a great engine, but it's also not an
unreliable lemon, by any stretch, either.