Say what you want, think what you want, but a 250 EUR prize pool simply won't attract many players. Non-regular members might even think several times to join or not to join.
For me personally, I would join in whenever I have the funds for playing, regardless if it's 6 winners, 7 winners or 9 winners - but I'd skip if only 5 placings are available (almost no chance of my getting a winning spot, that's why).