Is Futari much more difficult than vanilla?
i guess you're talking about PS2 Mushi
IMO, first Mushi was harder (considering the nature of the port, it wasn't near arcade perfect at all: laggy controls and BLURRY, it was confusing and almost unplayable)
the scoring system is easier to understand, the accuracy from the original arcade PCB is higher (that means you won't have to stretch your eyes to see what's coming on you, and there's a Novice mode too
in terms of difficulty as bullet patterns, depends on what version you're playing, it goes like this from easiest to hardest:
Novice > Arrange (uber easy: giga wing gameplay and autobombs) > 1.5 Original > 1.5 Maniac > BL Maniac > BL Original > BL God > 1.5 Ultra
Arrange, Novice and 1.5 are available in the disc, Black Label will cost 1200MS, but trust me, BL is fresh air compared to the rest
so the second one is "easier"; you know what you're doing, you know how to score, and the controls are responsive, even with the 360 stock pad i can 1CC 1.5 and BL Original without much problem
if you're thinking about getting the game.. what are you waiting for???