They're pretty good. They're fairly noisy (not like a gen-x or anything, but much louder than a eheim or laguna). They run kind of hot.
The air to watts ratio is fantastic, and the air to water ratio is quite good.
If you want the same pump for a 1/3 the price, the quiet one 3000 is identical to the sicce.
IMO, at this point there's no reason to use skimmer pumps other than the askoll/laguna based models. You can buy a laguna powerjet 1500 for $150 vs the sicce for $125, and the laguna will get easilty 1800 LPH of air vs the sicce's 1000, will have a better air to water ratio than the sicce, and be much quieter to boot.
Sol