Why is set_rx_format not implemented for USRP2?

Hi everyone,
I would like to set the data width to 8 bit I and Q (instead of 16 bit)
on the wire when receiving data from the USRP2 to be able to receive a
wider frequency range. I found the set_rx_format() and set_tx_format()
functions in usrp2.h but they aren’t implemented. My question is if
there are any particular reasons why this functionality isn’t
implemented?

I am also assuming that it is possible to set the decimation rate to a
value less than 4 (when the gigabit ethernet isn’t the bottleneck and
also assuming the host computer can handle it), is this correct?

Regards,
/Ulrika