Ah right. Richard did mention an official CoC WW1 that might be released at Salute and I did wonder if it was that one. However it’s all gone quiet on that front at the moment.
CoC is closer to IgoUgo than the more random card driven M&B. As Simon says you could split the table into sectors and run them in parallel. For M&B you can draw more than 1 card at a time(resolve any simultaneous actions by highest status or role of dice?) and it might be worth trying CoC with simultaneous turns and resolving conflicting actions in the same way.
Triumph and Tragedy works in a similar way to card driven mechanisms but allows you to stack your cards in a preferred order and play them according to individual unit initiative. Again you can allow 2,3,4 players at a time to perform their actions and resolve conflict via initiative.
Not sure there’s a major problem with any of the sets compared to standard IgoUgo, which means you do hang about while the other side takes their turn and in our bigger games usually means we ‘sectorise’ the table to cope with slower players (or those players who have a lot of cavalry to take off the table).