.------+-----+-----+-----.
| Crit | 20% | 30% | 40% |
+------+-----+-----+-----+
| *1.3 | 26% | 40% | 52% |
| Diff | 06% | 10% | 12% |
+------+-----+-----+-----+
| +10% | 30% | 40% | 50% |
| Diff | 10% | 10% | 10% |
'------+-----+-----+-----'
*1.3 (or *1.1) - multiplier - scales with crit gear, while a flat +10% - addition - does not. Therefore I propose the latter.