The X4 might in a very rare case go out. Many people use them at the track in my area and I've never seen or heard of a single issue.
Buy four of anything from HobbyKing and the odds are not in your favor of having four of them remain working (just search the forum on "Hobby King") over the long run or even the very short, out-of-the-package-run.
If you really want to separate everything out of one box to create redundancy,
order several of these AC/DC LRP ones that Associated is clearing out. It won't be cheaper but everyone of those you buy will outlast everything else you own RC-wise right now.
This charger question is like the difference between buying disposable razors and a good electric. You'll wind up shaved either way, how you get there will be personal preference.