Just my opinion ... but the design of a charger that takes 220 VAC, through a full wave bridge, and does a buck convert down to the proper voltage to charge the battery pack is simpler ... and more importantly cheaper .. than a buck/boost topology that needs an inductor for the boost.
The battery pack cost does not appear to change much whether you do 99S2P or 33S6P. You still need about the same Amp-hours to go 1 mile. The price of the contactors, fuses, insulators and IGBTs is lower for lower amps and higher voltage. I'd like to see a bit more circuitry checking for frame leaks, and more contactors isolating sections of the packs ... but perhaps I'm paranoid.
700 - 800 ish VDC for the 460/480V 3 phase input to DC bus
900 - 1000 ish VDC for the 575/600V 3 phase input to DC bus
Wolftronix (youtube handle) is working on an arbitrary (likely reasonable to boost 5x, buck 10x) DC/DC converter using a Prius inductor. I have not seen any update posts on it lately
Last I saw, he was trying to use a 48V pack to power solectria controllers (which he repairs) and perhaps fool a DC charger into thinking it was charging a 144V pack when it was connected to the converter and actually charging a 48V pack.
Interesting stuff. Even with his experience, I would expect some smoke to be released from some IGBTs ...