Good analysis but if it takes 500' for it to return a grade figure then it will miss or report inaccurate results for climbs shorter than that. Where I ride there are many climbs shorter than 500' where I'd like to know the grade. Garmin may be trading off something to get quicker results but I've found my 800 to be reasonably good at grade reporting.

I wonder why bike computers don't have pitch sensors like most cell phones do, which give instantaneous display of pitch. Waiting to gather rise over run data from GPS and/or speed sensors seems non-optimal.