I'd be surprised if it was not allowed - trying to use a 50 quid transciver from argos to contact london information would be CRIMINAL. but for chat i shoudn't think it matters.
These devices are for people to keep in touch with out useing there mobile 'phones - and so they can go 'round with a hissing box tryin' to look important. so for air-to-air chat use i really see no problem.
Also let us consider the frequency these things use - a multiplex on 418Mhz - it's not going to bother people how these things are used as long as, like i said before you don't try to do something stupid - like, god forbid try and use one as you're main transceiver (you'd have a job trying to make them run on 108 - 140 mhz anyway, and they don't use fm, they use binary code decimal
)
Maybee one of us would like to try seeing if they can make a headset run in one of these things - if you can, fair play to you and don't forget to tell us all how it goes!
WelshFlyer.