At the moment it seems like a big jump going from one level to another especially at the 4 and 7 breakpoints. What if instead of having to deal with the full affix outright, the affixes got progressively stronger as the key level increased? Here is a rough idea just to illustrate the point (numbers not set in stone):
Levels 4/5/6:
Bolstering - Now increases health and damage by 14%/17%/20%
Bursting - Players now suffer 8%/11%/14% of HP
Raging - Mobs now gain 60%/80%/100% increased damage
Sanguine - Mob heal amount reduced by 20%/10%/normal amount
Teeming - Remains as is
Levels 7/8/9:
Explosive - HP is 70% of normal/85% of normal/normal HP
Grievous - Damage taken is 70% of normal/85% of normal/normal
Necrotic - Reduces healing by 1.5%/1.75%/2%
Quaking - Damage dealt is 20% less/10% less/normal
Skittish - Threat reduction is 20% less/10% less/normal
Volcanic - Damage dealt is 20% less/10% less/normal
This would give players more opportunities to better learn the affixes and not be so overwhelmed once they hit the breakpoints. It would increase participation at the lower end and the progression curve would be smoother. What do you think?