coralife skimmers are good skimmers for the money, sure they make better ones but you will also pay 500+ for a good one.
i have the ss220 and i think i paid ~160 for it off bigals.
only time my skimmer has overflowed is when the water gets a little low in the sump from evaporation and the skimmer pump starts to suck a little air, that seems to give the needle wheel pump a good kick and can easily overflow the skimmer. thats what i have seen with it anyway.
if you have the cash for a euroreef (etss) than i would go with that, if not coralife should work fine.
edit: the only known issue i know of with coralife is the red adjustment knob can start to leak, but if you pull up on it will expose the o-ring that you can put a dab of petrolium jelly on and that will stop it from leaking.
johnson and johnson makes some petroleum jelly that is petrolium free, for a lack of better words!