I use the Iroshizuku ink in my Pilot Falcon & it’s always been very well behaved. I haven’t used very wide nibs much. I have a couple of calligraphy fountain pens at that sort of width, but every time I stop using them for more than two seconds, the ink refuses to flow without a tedious lot of cartridge squeezing and coaxing. It ends up being more bother than using a dip pen.