I watched a stream from Wai Wai arcade yesterday. Best run I saw was 702 billion in EXA mode/Kiwami, up to the stage 5 boss. The scoring looks like a mix of Espgaluda and Progear (but mostly Espgaluda). There also seems to be some shot change mechanic like Futari Original/Ultra. You have a stage counter and overall counter on the lower left. The overall counter flashes and switches between red and blue until you get over 980000 (it maxes out at 999999), whereupon it changes to yellow and the shot change mechanic seems to go away. When you die or bomb, like in Futari, both counters reduce.
I saw someone playing Zetsu mode and it looked like it ran faster than the X360 original (some Japanese guys on the stream also commented on this). Less slowdown, and the slowdown that was there looked choppier. Not a big deal, the X360 version is less than 50 bucks, so just play that instead. I didn't see anyone play the original Akai Katana, unfortunately. I hope the slowdown accuracy is better there.