I've been testing them lately and yeah it does seem that you get ~10% profit after curation cut. Thing with them is that if someone else overbids in the same voting window as you your ROI can drop down all the way to -5 to -10%, some don't even have a lower limit.

But yeah... what you said stays true for them as well, that's why we decided to create something different and soon we will be experimenting with a different kind of bid bot as well with different rules but still non-profit and having the buyers best interest in mind.