After about 9 months with a Bose X in a S61, I went back to my old DC. It produced a resonant feedback if the sliding window wasn't perfectly closed, had poor battery life and just didn't seem to cope well with the low frequency noises in the S61. Other pilots agreed with me, while some others loved it, so it may just boil down to head shape and earphone seal.
It took a while to go for it, because of the above, but I've recently bought a new A20 and I'm using it in a Super Puma. So far I love it and it has given no indication of similar downsides, but it's not comparing like for like aircraft-wise.