As someone who has been sumpless until recently, I can say the sump is a huge plus. I had HOB filters and skimmers for years and the performance of a sump skimmer vs HOB is night and day. Additionally the added water volume can help especially on a smaller system.
I had my drilled 180g plugged with a 40 breeder sitting in the bottom for the first year empty with anticipation of setting up a sump in the future. I just set it up a few months ago with the Eflux return pump you listed and the baffle Fiji cube baffle kit. I honestly should’ve upsized my return pump, but got a really good deal on it. Working on established a good refugium now, but the nuisance algae seems to be out competing my red macros currently.