Hi Jonah,
I still use one of their original Sparticle kits which uses a YPW01 250W motor on a 24v battery and I am extremely happy with its power and performance, so much so, that I am also in the process of converting my friends Brompton the with last 8fun Bafang offering and I am going to convert my second conventional Brompton with a Crystalyte 209 all of which will run 24v.
I cannot comment on the latest kit they produce.
They don't give any details of the new motor apart from being a Permanent Magnet Brushless, 250W to 960W, 13 to 26mph i.e. the motor is capable of being over volted, imho not an option for the Brompton even if you welded the motor shaft to the forks!
The standard battery option is 26v,15aH but they do offer a Power upgrade option for Overdrive and Xtreme version, which I assume would be illegal to use as an ebike and I think is what you must have seen.
I suggest you contact them for more details.