Good points. What they DO pack into these tiny chips is truly amazing. I just wish someone would dedicate two pins on the package to IF out and IF in, so that one could add a 1 MHz filter with steep roll off, to augment or replace the internal dsp filtering.
I had not thought about the phase noise of the LO--Normally 2FSK systems can tolerate a boat load of phase noise.....I wonder if I replaced the cheap onboard xtal reference oscillator with one with good phase noise, if my "jammer suppression" would improve?