I'm only a colonel right now (soon to be general), so it will be a long time before I'm a marshall and can get the wind runner. In terms of power I am 25th on my server, but a long way behind #24. If I started now (I have 600 M coins), it would take me 7 months to get the aurora. If I start saving when and if I buy the dragon (in a couple weeks), it would take 9 months. Intuitively, I think that the dragon would help me earn more coins/day than runes.