Progress on 1 is milder than M34.
That said, probably my mildest razor is the Star Tech clone which has a miniscule blade gap and only ever so slight blade presentation beyond the top cap, and that razor delivered one of the closest shaves I've had in a long time the other day. If you use the top cap as the guide, rather than setting angle as a relationship between the comb and the blade, you can get the same shave out of any razor as the blade gap becomes irrelevant. If anything the blade presentation is of more importance (that's how much blade sticks out from under the top cap) but only for how much "chatter" you might get. Again, the Star Tech clone with very little presented beyond the very blade edge is perfectly capable of a very close shave by following the angle from the top cap ... in short, it's not necessarily the razor but the technique.
Thinking outside the box, how about you shave your neck with a cartridge (which I believe you've said didn't/doesn't give the issues) until those issues clear up. Carry on shaving your face with your DE. Another thought is, the neck can be a point of focus for sweat and dirt - you've said that under good light you can see hair growing through the skin where you have the issue, so maybe try something more alcoholic than a balm on your neck or cutting out all aftershave products, so just the alum and clean water. It could be as simple as a reaction to the balm.