Whether a mouse is comfortable is quite an individual thing and depends for example on what kind of grip you use. I use claw grip and a major factor for me is weight, the lighter the better, as I lift it a lot. I had a glance at those two mice and one thing I noticed is that the new one has quite a bit larger dimensions, so that might be a factor.
The Souls games. I really like those games personally, but the community does seem to lose their mind a little anytime someone criticizes their difficulty or suggests something like an easy mode.