The sampler kit is good if you want to do one or more of the following;
A) Switch out a switch (or just stem and spring) on your existing board to get an idea of what a switch is like. Playing with the switch in your hand might give you a rough idea of the differences between linear and tactile but that is about it.
B) Have a play with O rings - Even though 5 of each is hard to tell what typing will be like and for the price you might as well just buy a full set.
C) See what all the colours that WASD offer look like in real life.
D) Fill out your collection of random keyboard stuff
If you live somewhere near a large computer store they may have some mechanical keyboards from the bigger brands (in components, not necessarily mechanical keyboards) such as Corsair or Razer on show. I live in the UK and I know a few PC World Stores (yuk!) have some boards out, they are mostly if not all Red switches though.