The hashrate is not 300 MH/s over 24 hours. There were miners mined at stopped mining over the past 24 hours. 300 MH/s is just the current hashrate. The current running round with 0.34 BTC invested and 300 MH/s is 3. The link here: http://multicoin.me/history/2 shows the finished round which is round 2. There was 4.06 Bitcoin invested and 2.85 BTC generated from miners that round.
There are 0.34 Bitcoin invested from Investors this round and 3.76 Bitcoin generated from miners this round. The price is calculate very simple: Total bitcoin generated from miners and investors of the previous round divide by the total number of MUL sent out. So there is always enough BTC for the ATM to fulfill cash out requests.
All right, for round 2, 0.34 BTC came from investor while 3.76 from miner. So that 0.34/(0.34+3.76) or 8.3% BTC came from investors. The link below says 58.76%. http://multicoin.me/history/2
Besides, round 2 has about 300MH/S on average according to your site but generate 3.76 BTC over 24 hours. The efficiency beats every multipool on the market by a large margin. Is it right? http://poolpicker.eu/text.php
EDIT: the ATM setup solely depends on your estimate of multicoin price. If you inflate the amount of BTC being generated, this coin is just a scam.
How is the 0.34 BTC from investment being able to generate 2.85 BTC? If such is the formula to calculate multicoin price, how can you make sure the ATM has enough BTC to supply for cashing out request?