For the upper receiver section in the image below. When IQ Out is selected, the switch goes to IQ Out. Data no longer goes to the internal Digitizer (lower part of the image).
ThinkRF WBIQ option has 160MHz bandwidth, the internal digitizer doesn't handle such bandwidth.
The analog filters used for WBIQ variants are wider than those used in the standard products.
These filters have been designed for use with wideband digitizers and are not suitable for use with the internal digitizer. If used with the internal digitizer there would be a significant amount of aliasing.