Crit to bard is the same for Spell Speed to BLM as we get more procs if we have more cast. We also have infinite mana source due to our job mechanics. To me, it's important to know because of Zeta. Since for BLMs, you cap Spd first and for Crit/Det it's a ratio of 1:1, Det is obviously better. You can swap gear around to get 292+ Det easily except in T13.

Now... according to that link. Spell Speed decreases the value of Determination. That would explain why it's so low compared to Summoners since we stack Spell Speed and Summoners spit on it. Even so, wouldn't Crit be better by default since in current gear if I take an head slot for example, it's 14 Det versus 20 Crit. Even if the value of Det is higher than Crit, quantity wins in this scenario.