used my Lightspeed Zulu so far in Bell47, R44, AS350, AS355 and Jetbanger. All work well but I did have some problems initially with 'buffeting' when I moved my head or when I was eating food; I bent the headband a little to make them fit tighter and they work a treat now.
Not sure on the doors off situation - would recommend you try a pair before committing to the purchase of them for this use but the passive suppression is far better than th Bose (which I sold to buy the Zulu).