I see what you're saying. It still looks OK to me, but I will try the same without detail on.
Even though the overall image was under exposed (due to the low lighting), there was a weak spot light in the ceiling just above the guitar. This is where the over exposed blurred highlights are coming from.

It was a lot worse until I slightly closed down the aperture to bring back the blown out blurred highlights caused by the direct spot.

Don't get me wrong, the original is fine but i think turning detail off turns the camera into an althogether different beast and the more 'off' shots i see the more im convinced by it.

I hope to pick one up next month (stock willing)

cheers
paul