I dunno man, with all the talk I've heard about Volts and inconsistency I think you should be pretty set with the Crave but a Fission Volt does get close to Crave fills the gap to a regular Volt. I like mine but it's not a turnover or powered down driver. Looks like more redundancy to me, I'm also not tossing 450 though.
I can't remember if you lost your Inertia but Insanity and Wrath are on both sides of it stability wise. I didn't click with my single insanity I bought it was too much like my Inertias but tended to pan wider but you might like em probably a very controllable turnover driver in plasma, stable Vanish flight. I guess I'm not sure what shot you're missing. You are either overthinking speed ratings or you need a technique distance driver that powers down.. It looks like your straight / stable slots are covered.
Plasma Wave is easy distance good glide, fill a gap from Relay or replace the Vanish. An Inertia is a distance driver that powers down well from fairway to distance duties but doesn't pan a anny like the plasma Wave does. A 150ish plasma Crave is the bridge between the Crave you have likely and the Relay. I've found the Crave and Volt redundant at my distance the Craves just easier to throw less distance.