A proper helo headset will suit helos better (!) as the noise attenuation is much greater.
Adaptors are all well and good but treble or quadruple the number of failure points so my advice is avoid if at all possible.
Best solution is surely one headset for helos, another for f/w.
I'm told impedance differences can cause a problem but I've never suffered it (I used adaptors for helo headset in f/w for years). What I did encounter though was different earth protocols which may render a headset/adaptor combination unusable altogether.
Peltor are probably still the best for lightness, toughness, noise attenuation and comfort. DCs are ghastly things imo.