I can't explain the Passmark vs. Geekbench score discrepancies... But a 10% increase between the i7 options sounds about right to me.
I was going to get the i5 before I found out about the quad-core CPU in the mid-level Mini. But the $200 difference in price seems to be a No Brainer. Add 16GB RAM and it should be a Very Nice Mac (and a substantial upgrade from my current 2006 24" iMac!)