r0ach = Half of BTT? Well maybe there are lot of sock puppets on here, lol.
Anyway, I don't think you can easily answer "how much reputation" cost, but you can't say that failure to take short term advantage is not a Nash equilibrium when reputational costs exist, because that is an alternate consistent explanation.
Miners can be anonymous, they can collude, frankly saying, this "reputation" topic doesn't look as a solid counterargument against the claim that Bitcoin operates out of an equilibrium.