Hi there
We find most DDR4 kits are all very overclockable, rather unlucky if you can't achieve 3000MHz from any kit.
Also prices have now come down so much it now makes no sense to buy the slower stuff to save just a couple of quid and is better to spend a couple quid more for some much faster and nicer looking memory.
Oh I agree, I just haven't bothered to try for more since I guessed 2666mhz with 12-11-11 timings would actually be faster. I have seen others doing 3333mhz on these with looser timings.
I really didn't spend much time overclocking it, and £109.99 3000mhz RAM is about 40% more expensive, I don't think its money well spent. I have simply set it to the settings above and just left it since then, same as I could probably do more than 4.4ghz, maybe one day i'll give it a go.