As Silverblade posted his settings twice I guess I'll put my question/comment twice too -you dont have to read/answer  it twice:)
I dont understand the logic of having min rays = max rays. As I understand it from the description in the manual, the process is (whenever you have the options of min/max rays &threshold):

1. send the minimum amount of rays
2. check threshold - if it was achieved stop.
3. if it wasnt achieved, continue to send more rays till the max number of rays was achieved or the threshold was achieved, what ever happens first.

So it makes sense to start with the  smallest number of rays you can in the hope that the threshold is achieved and you wont have to send any more. If you chose a too low number it will have to keep checking if the quality is met(that takes time too). So if you know by experience that a certain number definitely  wont do the job, set it higher.
Max number should be bigger than min number, so it continues till a good result is obtained.
Logically  the process should stop when the required quality is achieved, not when the max rays limit is met. The 'max ' is only there as a precaution, in case the resources dont allow you to achieve the quality you want- you dont want it to run forever.

In your setting it will send 400 initial  rays and then check for the quality threshold. if the threshold was reached it will stop - but maybe a lot less would have been OK too, it never had a chance to check earlier. If the threshold wasnt achieved - well too bad it will still stop anyhow because the max number =min number was achieved. You might as well set the threshold to 0%.
(It would be nice to be able to get some feedback from the program as to the reason it stopped sending rays on average - threshold achived(and how many rays where needed) or  max number achieved (and what was the threshold when that happened). Would be easier to learn what a good strategy is. I guess that is too much to ask from e-on developers?)

Of course, it is entirely possible I didnt understand the process correctly - please enlighten me:)

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