Simon 150 - you mentioned doing the maths. Some time ago I did just that for a "typical light aircraft", assuming a limiting g of 4.4g clean and 2.2g with flap down. The graphs illustrating the results were most illuminating for me. In particular, max rate (level turn of course) is indisputably achieved at full power clean. But if you want min radius, it doesn't make much difference whether flaps are up or down. I have found that fact useful for scenario based training.
If you like, I'll PM you the spreadsheet with graphs attached. (If I can attach files to a PM that is - if not, send me an email address.)