Mentors are great, but cash is king. Unless they can credibly get real angels to write first checks, it'll end up limping along, the same as LaunchBox Digital and DreamIt Ventures. Sam Yagan and Troy Henikoff are the real deal and both gave me great advice when I was doing my startup in Chicago, but at the end of the day, I judge accelerators and mentors by their ability to get startups credible angel flow. YC and TS are the only programs that have solved this problem.
That said, summer in Chicago is the closest thing to heaven on God's green earth and $20K is $20K. Nothing stopping you from leaving Chitown after the program's over.