Originally Posted by
Ultimatecalibur
Due to how multipliers work, the difference between +3k Crit, +3k Det over min and +3k Crit, +2k Det & +1k Ten over min is ~.75% less damage and potency based heals (i.e. heals like Storm's Path), a ~2.4% net increase for damage based heals (heals like Nascent Flash) and a 3% reduction in damage taken. As long as Determination and Tenacity are roughly equal you end up with a fairly significant increase in survivability at a minor cost in damage.
The biggest actual factors in Tenacity sucking is actually the fault of Crit outperforming both Determination and Tenacity by a wide margin. Crit, due to being factored twice into damage calculations, ends up having escalating returns on damage rather than diminishing returns. Going from +2k Crit to +3k Crit is a bigger damage increase than +1k Crit to +2k Crit. It starts out worth less per equivalent amount of points but quickly ends up worth more per amount than all the others.