MrSavage - 2:19 pm on Aug 6, 2011 (gmt 0)
You need to consider first that Mr. Google is reading this thread. Why wouldn't they? It's a great counter strike.
I would say, it's a bad idea in my opinion. If you do find your original site punished with a penalty or drop in rankings then what? How do you know what triggered it? That pretty much means those domains you 301'd likely have to go bye bye. At that point what happened to the original domains trust in Google's eyes. That's taking a hit.
I've heard Cutts say in the past that 301's are okay, but if there are lot or an odd pattern, they will look at those more closely. It's also pretty damn hard to keep a domain sale a secret from Google. I'm sure they are especially good at that game. Afterall, if what you're talking about was successful 50% of the time, it would be more than a small problem.
I can say when I've bought a domain the rankings went down the toilet, or reset to zero as Tedster said. Those were without being able to keep the original content. If you can keep the original content as is, then maybe worth doing. Very slowly would be my advice.