I just spoke to someone I know whose bike has electronic gears. Batteries dying can be a real problem, but neither they nor anyone else I’ve heard of has ever had problems with liquid ingress or servos wearing out; I think those are largely fake scaremongering, at least on reputable brand bikes. In fact from what I’ve seen, water and dirt are more likely to cause problems for mechanical shifting than for electronic.

As for the shifting, the person I spoke to said yeah it definitely is noticeably better, but not so much better that they’d have bothered with it, if it weren’t for the fact that the bike they were getting only comes with electronic gears.