Here's some really comprehensive data on transmitted noise characteristics for many current transceivers. If you're wondering which radio would be a good choice for stringent multi-transmitter applications such as SO2R contesting, Field Day operation, or simply not bothering your nearby ham neighbor when you're both on the air, you may find this of interest:

http://lea.hamradio.si/~s53ww/TX%20noise/TX_noise.html

73...
Randy, W8FN