Update: Apple released the iOS 11.2.5 Update today, I recommend it for all Apple Pay Suica users.
The first full day of Apple Pay Suica with iOS 11.2.5 beta 1 and restored Suica notifications on iPhone X has been good. Actually it is the best Suica performance on iOS 11 so far, on par with iOS 10.3.x in terms of speed and stability: no gate error flicker, solid store transactions even with those pesky Ueshima Coffee shop readers. JR East can kiss that Apple Pay Suica notice goodbye.
The best part is that iPhone X Suica performance finally achieves iPhone 7 on iOS 10.3.x levels: it just works. I really hope iOS 11.2.5 beta Suica performance improvements make it into the final release intact.