The point that it's been a lot more complicated than just Koven - High - Chris - Viper is definitely worth making, but I don't know if aoe-elo should be seen as the ultimate authority on this. Obviously there's no perfect metric for "Number 1" but I can't really see a serious case for Hera being it at the moment, and I think he's there more because he doesn't suffer (many) upsets and his wins tend to be stomps.the history of number 1s in aoe-elo.com goes:
08/00: RD_ChampioN
08/00: High
08/00: MoZory
08/00-10/00: Koven
10/00-12/01: High
12/01: MoZory
12/01: Koven
12/01-08/02: Grunt
08/02: Koven
08/02-11/02: Grunt
11/02-12/02: Halen
12/02-05/04: Chris
05/04-08/05: Chris and DauT very close
08/02-01/10: Chris
01/10-10/13: DauT
10/13-08/20: Viper
08/20-present: Hera
Also, to nitpick, Viper overtook him again very briefly last month.