Note that the version with function keys has a 2.0 GHz processor and 1866 MHz RAM, compared to the base touchbar configuration with 2.9 GHz and 2133 MHz.
You can configure it up to a 2.4 GHz i7 for $300, bringing it to the same price as the 2.9 GHz i5 and touch bar. I don't know how those two processors compare.