Personally i think the lockdown throwdown cups were on the right tracks cup wise and not soo much the dreamhack one, but not because the layout was wrong just because in the lockdown throwdown ones the lower end teams still got to play in a play off system / group on the second day.
Lockdown throwdown 1 for me saw an almost perfect system. Groups on the first day and playoffs on the second but also placement play-offs for all the lower end teams that dont make it through into the invite bracket ro16. Giving the majority of teams something to play for and a good second day of solid match ups of their own level (ish). It did unfortunately fail to cater for the top end teams that arnt quite prem seeing the same issue as the Dreamhack one saw that Charle mentions above leaving them knocked out straight away in the ro16 after winning the groups.
Lockdown 2 was pretty much the same but ended up with a 2nd day placement based group rather than playoffs (maybe due to sign ups / possibly due to teams not realising it was a thing) Personally id rather see it go through a proper play off layout on the second day even for the lower end but even the second day group meant decent games on the second day for almost all involved. (This one still having the same winning group cos you are d2+ and getting knocked out straight away vs invite team issue)
Dreamhack didnt see anything for the lower end teams on the sunday which for me took the enjoyment out of it and meant for a less serious approach to the saturday games (we used a random class generator for most of it) unlike in the lockdown ones where you always had something to play for.
Though we all love seeing the top end teams playing it out for me all the teams participating should get to run the "tournament experience" being group stages on day 1 and then placement play offs with pick bans etc etc bo3s on day2.
I am not sure what you can do about the winning groups and then getting knocked out in the ro16.
Obviously i am fully aware it requires a fair bit more work to implement what Lockdown Throwdown 1 had along with sign ups always being an unknown but im not suggesting that anyone should simply start giving up their time just so i get to play in a 2/3rd place playoff system on a sunday afternoon but for as far as tournements go for me that one almost nailed it. It was great fun and competitive.
I hope all that makes sense. Ive rambled on abit more than i expected. Thats just my two-penny worth, i could be way off the mark but thats what i got from the last 3 tournements.