Andrew R Stewart 

Vintage brakes work just fine and for a long time if set up well. Redrawn cables and lined casing, modern pad materials and an understanding to how to center them are the leys. Their power will be limited mostly by the leverage the dimensions create. A lot of younger wrenches haven't had to learn how to set up classic single pivot side pulls for max performance since these days they are mostly found on cheap and/or old worn bikes. Usually the finicky aspect is the centering. With calipers of any basic quality the centering isn't hard to do. If needed this can be described later.

As to whether the TRPs provide twice the power of the lower cost calipers. NO. Given the same set of dimensions (levers are the same, the reach and pad placement are the same) the power will be very nearly the same. If the leverage (that's all most calipers are) lengths are the same... Only when there are additional design elements like a cam driving the arm's movement will the clamping leverage change to any large degree. The usual reasons for higher caliper costs are materials, finishing and marketing. With the last item the most important. Andy.