How much harder is it for an SFBA investor to keep up with what's going on in a Berlin or London startup vs, say, an Atlanta or Miami startup? As long as you need to board a flight to get there isn't it more or less the same, whether that's a 4 hours flight or an 8 hour flight?
However if you're far away it's harder to keep up with what's going on with your company and many will not want to deal with that.