Just to clarify for talkdownman (and maybe others)
First, the simple mode-s that is required for private small planes does not really send that much downlink data, besides altitude, squawk and transponder ID (ac reg).
It is not required to send position or any related parameters.
Secondly, the mode-s protocol is much better and contains both better bit encoding and checksums. This leads to less mistakes in decoding, which leads to better TCAS and better ATC awareness, which leads to better safety for everyone.
I would go for mode-s any time...