I actually tend to be Quameno as well. Their racial victory conditions are very easy to satisfy and their 90% research bonus is impossible to match. Those reactors are something else as well, being so efficient that it's actually not necessary to divide up your fuel consumption.
Their growth rate isn't that helpful and other races can definitely reach max pop faster, but even the Quameni gets there eventually. My goal is to non-stop zero tax at least until 2110, at which point I'm well beyond 15 billion people, possibly billions beyond depending on immigration and starting population. With medical and rec facility, I'm seeing 16% homeworld growth rate on quality 100 planets and 15% on quality 90, which I think is "fast enough". It's not quite Gizurean, but it gets the job done.
And if I can be anywhere close to 24-25 billion around 2110 (with "close" meaning "within a few billions" and "around" meaning "before the end of 2111"), then I think I'm doing quite well. I'm way ahead on population, and once I get the Bakura down, I can produce colonizers (once I get them researched) way faster than Ackdarians. And once I get the Bazaar done, I can even afford doing it. With invasions going on and with all the ocean worlds getting colonized in short order, leading to a boom in civilian ship orders, I'm making very good money and can afford to zero tax the homeworlds I'm (hopefully) invading, which then leads to them also getting to the fun population sizes before the other far-away AI factions do. At which point I've got at least 3-4 times the population of everybody else.
It's not quite as deliberate as your approach, and very many very strong pirates generally are a pest since I can't afford adequate pirate protection fleets nor can I go offensive until I've teched up quite a lot and have long range scanners to tell me where to go, but aside from that it seems to work out well enough and not be affected too much by game difficulty.