The car I just bought is one of those ex-training cars.
It's actually in very good shape considering (like new all over), the only thing I am unsure of is the DCT. I'm not sure if the quirks are normal, or if it is a result of heavy use (I've been manual all my life, so it remains to be seen).
I did buy mine for less than 79k though -- and took advice from Zahir @ ZR Auto before buying; he also shares my opinion that a well-driven car is going to be a better buy than a garage queen.
Just check everything out before buying and use it's past history as a bargaining tool.
I'm planning on modding the crap out of mine, and it will be tracked anyway. I think my last 335i was driven harder than most cars, and was still solid after 46000k. These cars can take a beating.