The genelec website states that DTS-HDMA decoders apply a 100Hz 60dB/octave lowpass. I find this cannot be true, here is my 'proof' (from a PM conversation exploring this very thing).
More research on my part has uncovered this:
Two films which have HUGE effects at over 140Hz are Transformers:Revenge of the Fallen and Thor. Both have DTS-HDMA tracks. Neither of them has a lowpass applied when decoded by the AVR in my system, and those effect(s) are some of the loudest in the film(s). If a 60dB/octave lowpass was in place at 100Hz, those effects would be many more dB down.
TF2 (just over 120Hz, encoded to play back at just over 118dB):
These digital grabs match the analog grabs from the decoder in the AVR. No 100Hz 60dB/octave lowpass there...
I think there are sloppy mixers and good ones. Most everyone has a lowpass built into their sub amp or receiver, and I'm sure the mixing stage does the same, so square waves would appear much smoother. I set my LFE lowpass at 200Hz on my playback equipment to capture just such events as the ones above.
I could be wrong. But as far as I know, the existence of good, non-square-wave containing tracks (Tron Legacy's LFE channel has zero clipping), it makes me think it is a production mistake, not a decoding mistake, which is blinded by the lowpass filters on AVRs and subwoofer amps.