It's a matter of capacity. According to Colleen the regular bottle holds enough air for about 10 seconds of constant blowing. This larger bottle should last at least 2x as long, I hope even more. I would need some time to really tell the difference since my yesterday and today commute rides were unusually uneventfull so I didn't get to use it much. With the stock bottle I'd use it up sometimes during a single morning commute: 3-4 longer blows and a few short honks, and not have enough air left for the last couple of zombies wandering in the bike lane.
It's a little over-the-top hack, but hey, people already question my sanity so be it.