Well, I'm all for experimentation, but you have briefly touched on a lot of issues just there.
For one, simply "adding one more [sC] and upping the win criteria to 19" is not a trivial impact on the game; that impacts every power. I wouldn't be confident to mess with the balance and dynamics of the game without at least measuring the impact on every power in turn. That's going to affect the break-even line, and therefore the chokepoints will be affected in varying ways, and other such concerns.
It's a pretty thorny knot ... a gordian knot, I would say.
Still, in a while I will feel a bit more comfortable with the original gameboard. It is not really feasible to make comparisons when the basis for the comparison is not a known quantity ...