As suggested, I think reputations and achievements shall be shared with the alts (but an exception for achievements, the dungeon-achievement is what I mean, not the other achievements).
My own opinion:
- I think it supports to have alts a lot more, instead of seeing alts as a complete separate games, and becouse the more expansions we have, the more reputation there is to complete for the proffesions.
- I think it also benefits when being in a raid or dungeon, you can switch characer and still benefit the reputation for the main-character, instead of being "complete locked" to the character you play on, if tank or healer is missing. More social that way when being able to offer some extra alternative of playstyles when having alts.
And suggestion 2:
Why not implement so that a player can "exchange a character" when being in the middle of a dungeon, when a tank or healer is missing? It could work that way that all players must accept the exchange, and then it will cost the player himself 20-30 gold for the bonus of earning reputation and achievement this way of changing character right in the middle (the cost is for not needing to logging out/in, inviting, travel/summoning, and so on).
What do you think about it?