The lower capacity at higher draw is for when you draw right down to 10.5v. When you only run a high draw for a short time, the battery bounces back, so you get some capacity back for lower draws. Also the low draw times compensate for the high draw times. Works out close enough. Trimetric manual has some notes on why they don't bother with Peukert.
I ran some tests on this a few years ago and it came out like the Trimetric guy says. One of the other monitors does use Peukert but that is over-refined for the job IMO (and Trimetric's)
