Personally....
I transmit it as 'wun tousand', mainly to get it across without confusion. If you start listing off the same number, in my opinion its easy for people to get confused or misinterpret. Its like callsigns of XXX5333. I generally call them 'five-triple-three' as quite often you can see 5133, 5233 etc. and it makes it much less likely to be confused with similar callsigns.