BCP, I think what's happening is that pellet smokers burn their fuel just too fast. Both crucibles and pellets should be larger...think of a typical offset. (IMO Traeger was basing his cooker just too much on pellet furnaces.) Charcoal is basically wood that's had half its energy content burned out already. (And unfortunately also at least half of the smoke flavor as well.)
I suspect you had bluer "finer" smoke (
this Wikipedia article has a great picture of white milk turning blue with fine flour added) just because the crucible was a bit cooler using charcoal pellets instead of wood pellets, so indeed you had a better fire per se. (You didn't mention the cook temperature for your ribs, but I doubt you were pushing the 500-degree limits that the market for pellet "grills" feels they need to address, so of course you weren't starved for
heat energy from using charcoal instead of "full-strength" wood.) Alas, even though you had a better fire, the limitations of the stock pellet grill at impacting smoke flavoring to food are still there. Sorry that the smoke flavor molecules didn't stick to your food as well as you'd hoped.