Having a chilled out professional FI helps. When I did all manner of stalls for the CPL (turning, accellerated etc...) the FI was extremely experienced. His attitude was "well if we spin we shall recover, no big deal".
I did a bit of aero's a while back and the FI was a true professional. He'd find it funny when we were "falling with style" and start laughing before helping me recover. This instills confidence so you know that if you screw up, the worst that will happen is you'll have a laughing FI sat next to you...
Some of the more "fresh" FI's who are nervous and not really that competent do not fill me with confidence and there is no way in a million years I'd want to do any advanced stuff with them.