"I'm particularly interested in your Growler point. I have been expressing concern here for some time (or was it just some time ago?) about F-35 stealth in the multiband era and, without knowing enough about F-35 ECM, Growler would seem a sensible means of support"
I don't have a lot of insight into the F-35s jamming capabilities, but my understanding is that it is all in the X-band. L-band radars do not have the resolution to provide targeting data, and require very large apertures (i.e. very large antennas) to get even moderate angular resolution. But they can be used to cue other higher resolution (X-band) radars where to look for a target so they can put a lot of energy into a small volume of space (and perhaps from multiple different directions at once) to pry out the low RCS objects in that space. But aircraft can passively detect L-band way before the radar can detect the aircraft, so there are effective countermeasures. One would be to jam the L-band radar and prevent it from cuing the other radars. That's where the Growler comes in. Another would be to use a modified HARM type missile to take out the L-band radar or force it to shut down to prevent it being taken out. However, the missile would have far worse low angular resolution problems than the radar because of its much smaller aperture, so designing and building an L-band HARM missile would be problematic. The better solution might be to jam it and use cooperative passive detection to locate it and then put a big warhead weapon on those coordinates. With a big warhead, "close" is probably good enough.
Russia's PAK-FA (as well as some later Su-35s) reportedly carries an L-band radar. But with such a small aperture the already low angular resolution of L-band will result in very poor angular resolution on an airborne L-band. And as soon as the pilot fires up that L-band, every aircraft in the area will know there's a PAK-FA in the air and using cooperative passive detection, will know pretty precisely where it is. On the other hand, the Russians aren't stupid and maybe they've made a breakthrough that alters the basic radar equation for low frequency radars, or maybe they have tactics in mind that use multiple airborne L-band radars linked together. I've even heard rumors of modulating individual radar pulses and embedding data in each pulse so bi/multi static radars can generate a fairly precise 3-D picture. Who knows?
But the bottom line is that even in the age of multi-band radars, stealth platforms have a significant advantage. The question is, is stealth needed all the time? For middle east style wars against unsophisticated enemies, stealth provides nothing. If we get into a fight with a peer or near peer, how long will stealth be needed? The first day? The second? Once the ground based air defenses have been neutralized, is stealth really all that useful anymore? Maybe that's why USN is not putting all its eggs into the stealth basket like USAF appears to be trying to do.