Having extra camber helps the car to maintain grip in the corners. Having more caster gives you more camber only while the wheels are turned, which (it turns out) is exactly when you need more camber.
The Whiteline top-mounts installed easily. Mach V technician Tommy reports that they were no trouble to install; his only gripe was that the factory dust caps are slightly smaller than the holes they would go in, so he secured them with some urethane adhesive.
On the alignment rack, the car gained almost 1 degree of camber, ending up at -1.2 degrees left and right. Caster also increased by a little over a degree, to 6.8 degrees.
On the street the car feels the same -- I didn't notice any additional harshness from the stiffer hats. The car drives about the same, and I honestly could not feel the additional front grip -- the limits are so high that on the street it's hard to get the front end to wash out at all. A few tail-out donut maneuvers in an empty parking lot showed that the rear is just as frisky as ever.

If you'd like to buy a set of these nifty top mounts, you can (as always) find them over at the Mach V web site.