It's such a minor amount of triple and quad attack that DA is nearly not devalued at all, 1.164934 vs 1.17. TA and QA grant a 5.5% attack frequency increase on top of the DA.
17/2/1 = 1.234534
QA/TA no DA = 1.0696
17 DA = 1.17
It really isn't worth it in situations where accuracy would be a concern. Assuming even capped hit rate, you have a 73% chance to land 6 hits, and a 77% chance to land 5, lowering that further will sharply decrease the effective increase in damage over ele belt.
edited for clarification.