As it happens I have recently been using the inverse of these transforms for conversion in the opposite direction. We had been finding that the resulting RGB images were too dark until I changed the transform slightly (to a simpler gamma curve). This suggests that, perhaps, the current transforms are wrong (and may be inclined to generate overly bright images).

Perhaps we should try the modified transforms in DVD-o-matic and see how that turns out. Your Blu-ray test might be handy here...

Seen by a few people; still not me, and still not sure what is going on.

Are you using sRGB as standard color conversion ? This has a Gamma of 2.6 I think its too high.
I'm using the rec709 conversion with a gamma of 2.2.

Try this, perhaps it helps.

I'll close this, as it is old and we now have configurable colourspace conversions... anyone feel free to leave a comment if they still see the problem.