Interesting, thanks. I've been running with C5=0 on my MiniST2 and happy with it, but will try C5=5 and see how that feels. I typically recharge in the 2-bar range, but often with more in the tank than that.
EDIT: back from a 5-mile test. With C5=0, I can pull a maximum of about 1580 watts, setting it to 6 limited it to about 1250 and setting to 5 gave me about 1150. Both of those would probably be fine in most circumstances, but I really hated the 100% immediate application of power from a stop rather than the fairly-smooth ramp of setting 0 - almost dumped my front wheel into a hedge when cornering on a sidewalk at very low speed, as it leaped forward in PAS 2. That's a problem on tight, lumpy or slippery trails where a gentle application of power is necessary, so I went back to 0. This controller isn't as smooth on the ramp-up as the stock Rad tuning, but it's pretty good.
I moderate my usage and hold full-power in abeyance for those times it's really needed for a bit; usually draw in the range of 500-800w, occasionally hit 1,000 so I think as long as I keep my power draw under control my battery should be fine.
Altema here on the forum has done brutal motor testing with these controllers and said even when trying to burn out a stock Rad "750w" motor under repeated and lengthy full 1600 watt loads he was unable to do so, and as far as I know has not reported any battery issues, although maybe he just hasn't charged it enough times to notice. I believe he, like many of us, tries to keep battery level between about 25-80% unless setting out on a long ride where 100% is useful.