JJ, indeed it would have been so as the Mozzie proved.
Similarly Charlwood's book, No Moon Tonight, recounts one intercept where they dropped the 4000lb cookie for increased manoeuvrability and another, may be the same incident, where the gunners did not fire as the tracer would have revealed their position.
This certainly supports the idea that unarmed might have been better although the lookouts may still have been useful.
Remember a pressurised Wellington reach 42000 feet
http://en.wikipedia.org/wiki/Vickers_Wellington
and I found this too:
http://en.wikipedia.org/wiki/Victory_Bomber