>Does it work?
I haven't timed it, but I certainly don't think it's slower than using the inflation/stuff sack that comes with the mattress. I personally find it easier to put in X small but fast puffs with the pillow pump than Y larger, slower "whooshes" with the big bag. (Where X >> Y)
I've got 5.5 oz. plus 0.5 oz. for the stuff sack, but I'd question those based on the cheapness of my scale.
>When used as a pillow, does it hold air all night?
Yes; no problems yet.
It can make packing these mattresses lighter if you're taking two of them, no mattress stuff sacks, and one pillow pump to inflate them both.