Why do you want to swap out the stock pump? It’s well rated for medium to low flow through the filtration, which is a good thing. The return pump isn’t meant for flow as much as it is meant for turn over through the filter. And high velocity isn’t as desired in filtration. Don’t just upgrade things based on r2r suggestions, think it through first.
I had filtration issues with both the stock and the sicce 1.5. While I totally agree that according to the size of the tank the stock pump is sized correctly, the AIO chamber design is terrible and doesn't allow for optimal flow through the filtration. The idea behind a circulation pump is to push filtered water out and bring unfiltered water in and do so efficiently. When I had the 1.5 on there, it simply didn't pull enough through despite my wavemakers keeping food suspended for 10-20 minutes... After 3-4 days, my filter floss was still pretty much white in color. So I watched the tank for a long period of time after feeding, and most of the food was settling in/on the rockwork and sand despite going next to the weirs multiple times, leaving it to my cleanup crew to take care of. But because of this, I was always suffering from High Nitrates, like 50ppm+. So, I swapped to the 3.0, and now when food gets near the weirs, it gets pulled into them, and then into the filter floss... I can watch the process happen, just as if I had an overflow box.