Welcome to our forum Uguaga.
You may well be following the common advice of using a filter flow x number of times the tank volume. That is completely meaningless when it comes to biological filtration, which is where a sump really shines. Your 5x to 7x flow rate would satisfy most such standards that people use but a 600 litre per hour pumping rate would give just as good biological filtration. The other thing to consider is the like or dislike of your fish to high flows in the tank. I have Betta splendens that are widely known to prefer a slow flow rate and Ataeniobius toweri that are known to love high flow rates. Thank goodness they are not in the same tank.
The demasoni are probably ones who would also love high flow rates, based on their shapes, they are built for speed. That means the higher flow pump you have proposed would probably suit them well. I am not familiar with the other fish you have so I cannot comment on their preferences.
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