Having seen the success of big Rapidplay in the UK, I am still wondering why it didn't catch on in Australia. There was a push in the 1990's to make it a 'thing', including the Australian Rapidplay Open in Sydney, which had some big sponsorship, and an appearance by the Polgar Sisters. However it seemed to fizzle out after a couple of years, and hasn't really been tried since.
One obvious reason is the market for it. Players seem happy with weekend events with longer time controls (especially FIDE rated ones), or faster events like Street Chess. A single day rapid falls between the two, and so does not attract travellers from afar, or players willing to sacrifice an entire day.
Having said that, when I get back to Australia I may try and test the market, at least in Canberra. A single day 6 round Quickplay (as the ACF now calls it), with a time limit of G20m+10s per move, with a minimum prize pool of $900. $50 flat entry fee (sorry, no concessions) with 6 to 9 prizes on offer, depending on the size of the field. As it is a serious event, FIDE rating it is a given. I'd also use the English method for awarding category prizes, which is based on Score Achieved minus Score Expected, so as to reward good play and avoid the luck of the last round draw.
To make it work properly I would need to run at least 2 events, to see how it performs as a concept. The only other issue I need to work around is the somewhat crowded Canberra chess calendar. ACT Champs and Doeberl are to big events early in the year, but possibly I can squeeze it in somewhere.