Just used the keggle for the first time on this last batch. Even though there is much more metal to heat than my dinky old pot, I found it came to boil rather quickly, maybe even faster than my old 7.5gal pot.
I think the skirt around the bottom traps the flames when I turn it up, whereas they would lick around the edges of the previous pot.
Anyhoo, I like it. It was also fun taunting the hotbreak with "show me what you got!" instead of watching nervously with a spraybottle.