In my opinion, it doesn't sound as gratifying in LoL than in HoN. I mean, both cannot have the same way, but "Aced" doesn't sound as severe as it is to a team, compared to "Genocide," also the announcer in HoN only really sounds funny when he goes for the multi-kill moments increasing with each consecutive kill with one exception "Double Tap"(Most lulsy of them all, just because they changed it from something better), "Hat-Trick", "Quad kill", "Annihilation". I mean, they do give the player a sense of accomplishment because it's in a very gratifying tone, instead of this fairly quiet voice. LoL should consider making a new set of announcer sounds for the game, with more power to the voice.
This also makes me note another thing, but it's unrelated to voice, but I will mention it anyway: Multi-kills should be able to go up for a longer while, It feels kinda sad if you get a triple-kill and then a double-kill right after, instead of it going penta-kill.