I have spent significant time on the powerswitch skis in all their variations. Despite the nose thumbing from some, the system works. Is it like two different skis?....no. But it IS like a turbo dial. This means that you could turn (tune) the performance up or down according to snow conditions, your mood, or phase of the moon.
Trying to quantify this is silly but if forced at gunpoint, I'd say that the difference is somewhere around 10-15%. Another way of looking at this is that with the switch on, the ski feels 3-5 cm longer.
I think that for your size, any of the switchers would work well. Which one just depends upon your personal terrain priorities.