In the Banneret/PDK discussion: I was going to play one, but group friction caused me to leave right as we hit 3rd level, so I didn't get to test my hypothesis.
I get the feeling it'll be subpar if you play it like a support class, but would still be effective if played as a fighter (mostly because as others have said, the fighter chassis is pretty solid). Rallying Cry sucks as a means of in combat healing, but I find at that point second wind itself starts to drop off in in-combat usefulness. Instead, where it shines is as a supplement/replacement for the Bard's Song of Rest, as in exchange for not affecting as many people, after 4th level it'll be on average better, and after 6th level it'll be *guaranteed* better than Song of Rest. Best of all, the fact that they're different abilities means you aren't competing with usefulness with the bard as far as bonus short rest healing.
Now, does that make it an exciting archetype defining feature? Not really, but it's something I want to play around with more.