It's neat that this thread is still alive, I guess "do the math" vs "just test it" can be a hot topic. Relevant:
If we have the ability to test something quickly, I encourage it so we get something done. If it requires more analysis first, then we do that. Teams will vary depending on resources. Folks who manage to do both all the time are awesome.
Re: original post - did you test them? If so, what did you find?