No, a 5000 l/hr Sun Sun is not comparable to K4 at all.
I an still using 4 K4 and 1 12000 l/hr Sun Sun (2 heads one). Considering the 12000 is divided by 2, they are still 6000 l/hr. Its still not comparable to the K4. I made a mistake of getting these Sun Sun wavemakers when 2 K4 broke. Then I realised putting at same position, not matter how I face it, red algae and diatoms are growing at the further end of the tank. I'm pretty sure its dead spots. Once I changed back to the K4, algaes got blown away and gone..
IMO China brand's pumps are always overrated. When the state 2000 l/hr, it might only be 2/3 of that or even half. Not to mention, their wattage is much higher and heat is mostly a problem.