it is probably making that noise on space heating only because the boiler starts firing on low fire on heat call, and then ramps up if needed, on a dhw call the boiler goes right to high fire. that noise will only be produced with a low air flow in the vent. ..........i think
I'm thinking the 0011 pump might be a problem. That does have a high curve to it as far as head. I'v been using the 007 pump for short primarys because they don't usually have any head to speak of. I have had problems with the 0011 in the past due to manufactor reconmendation which maybe wasn't the best way to go. Check the size and make sure 0011 is the right pump for your application.
FYI I have hot water baseboard at home and I can hear a chine (ring) in some rooms but I'm just too lazy to fix it. Go figure, the cobbler has no shoes.