After getting encouragement from a friend that I was explaining my process to, I decided to start reusing my yeast. This revelation has taken me on a fun journey to a new aspect of my hobby, as well as thriftiness. I am not afraid to spend money, as my wife can tell you, but I am a huge advocate on reusing and not wasting. With in reason of course. My main hesitation was that I would ruin a perfectly good batch of beer because of contamination. I did not learn some secret trick that lessened my chances of ruining my beer, I only took a chance. The first yeast I saved after primary ferm was the yeast from the German Ale, which in this case is the European Yeast.
I've only reused yeast in one brew, which is the RBBCS. I have collected all of my yeast however, save the German Ale Yeast I used in the Pumpkin Stout. I did not reuse this yeast because of the potent nature of the beer and I would have pulled a lot of excess hops with the saved yeast. I did however use a technique that you might find a good alternative to reusing yeast if you are fearful of contamination. I saved about a teaspoon or two of the yeast I grew in the starter. I saved it in the same vial the yeast came in. This is a great way to save yeast to reuse with little to risk of contamination.
The other great place this new interest has taken me is to harvest yeast. Granted I've only done it once, but I was able to harvest the yeast from a bottle conditioned beer (Bridgeport Ebenezer Winter Ale). It was quite simple. I poured the beer into a glass except for the last bit, made a starter then pitched the yeast into the starter. It took 3 full days for the starter to start showing signs of life but in the end I harvested a tablespoon or two of yeast from the one bottle.
All in all my experience has been good and has added a great aspect to my hobby. The pros have been; I save seven bucks every brew that I reuse yeast from, there is enough yeast that I don't need to bother with a starter, I can even start mixing my yeast to make brews that no one would think to make. The cons have been... there is small residual flavor from the past brews the yeast was used with. It is so small that I can't really imagine it affecting the overall flavor. So no real con until I ruin a brew this way. But even then I won't know for sure if it was the yeast that did me in or just bad luck.