It reduces the effective wheel rate, but that happens because the force applied on the springs increases. You need to increase the spring rate to match the increased force transmitted from the wheels.
Don't confuse wheel rate and spring rate. Moving the springs does nothing to change the spring rate, it's the same. The springs don't care. But the effective wheel rate changes, because the length of the lever arm changed between the wheel and the spring.
So, the relocation lowers the effective wheel rate compared to the stock spring location for a given spring. To compensate, you need stiffer springs. Or a bigger sway bar. Or both.
