Bafang BBSO1B versus BBSO1B ETM

[strat]

I am contemplating a build with the Bafang BBSO1B kit. I understand that there is an extra torque model (BBSO1B ETM) available. Has anyone come across the ETM model? Does it provide an appreciable amount of extra torque? Is it heavy on the battery? As this costs an extra £100 in the UK, I would like to know if it is worth the extra costs.