This preview has the first footage I've been able to find of Sine Mora's most challenging mode, in which you have to deal with a difficulty-modifying rank system and enemies that release suicide bullets.
The Arcade Insane segment starts at 5:00 and lasts for about a minute. Looks pretty good. Not what I'd call "insane" (as far as survival is concerned, at least) but the ranks remains low for most of the segment and if the in-video description is correct the footage is from the very first level, so it'll probably get far more challenging.
Also, fuck me those suicide bullets are annoying. The way they twirl as they move forward irritates me to no end.