I will always prefer an older actor, who can actually ACT, playing a younger character versus an age appropriate kid-actor who sucks. As for recycling actors to play two characters in a show, I use to think it was always a mistake, until Deadwood proved me wrong. When they recycled Garret Dillahunt as the guy who killed Wild Bill, into the Francis Wolcott character, I learned my lesson. HBO shows seem to know how to do this stuff correctly.