The pre-selection is a big deal. The AD936x needs good front end filtering to reject n*LO. For instance 5x146 MHz = 730 MHz, which translates that 730 MHz nation-wide LTE signal smack-dab into the 2m amateur band. Unless they have a new front-end architecture in the AD937x, all the I/Q calibration won't help them.

Of course as you said, for $325 it's not a consumer chip, so some $ will be spent on external passives.