In my experience Overskilling scales mediocrely; not bad if you have decently well stats but not the best with low stats.. which makes it "useful" when you already have high stats - I may be wrong but that's how it's been for my experience. +X Skills can be super beneficial if you lack SPs in said skills; you kinda have to figure out if it is really worth it for your own needs.

The general thumb of rule when it comes to gearing is that you will always be looking for a higher item rating until you hit the rating wall (Push item ratings until you jump onto WT3; mid/max gear around lvl 55 and max gear around lvl 73 in WT4.) - the only real time where a low level item with +2 skill really outshines an higher level item is when you already have high stats (think around 200 in either or both Dex and Int) to begin with (or if it helps with your current Ability level).

TL;DR - +X Skills are flexible affixitions which can be useful when you have relatively strong stats or when you lack SPs in important abilities. You can say it outpaces higher level items when you really need it to; an item with stronger scalings (like both dex and int for example) is generally better unless you lack the necessary SPs to perform with the current ability levels or if it can overtune your ability performance if you have those maxed out. It really depends on whether you genuinely need it or not; whether you want to augment it further or it performs well enough that other stats (and higher level items) benefits you better - balance is key here.

Keep in mind that level has mainly 2 uses; specify which level a character can use said item and general scaling tied of the item to level table. Item Rating is the one that really controls how strong the item is; granted that it's loosely tied to the leveling table - I've had several items which I have used beyond several levels because they were simply too good to pass on in my build. Keep getting those Dex/Int numbers up friends~ hope this helps a little!