How well do you think the core roll would work with a d8 instead of a d6?
Pretty well, I believe?
That’s an interesting shift on the feeling of the roll, if you keep the same tiers. 50% chance of a weak hit, 25% of a strong hit and 25% of a miss on the first roll! That is cool!
The second roll becomes way riskier, though. Even if you roll a 1, you still have 37.5% chance of a miss on a reroll, so I believe the mechanics should address it somehow.