The Experience ladder sounds like terrible idea. The first few days, everyone is like: "Hooray, I cannot lose a pig." Then, they slowly start to realise that:
The last thing we need right now is splitting the players in twice as many queues.
This does not belong in the list because this is ten times more important than the rest. Let us continue - the players are going to realise that:
They have a favorite limit they are comfortable with playing. Winning and losing pigs at that level is something they care about. Dealing with downgrades and upgrades is a nuisance both ways (occasional upgrade under classic rules is rare enough to be a positive event that doesn't drain the supply of pig on the default level).
When they lose, they lose. The option of clicking the Game over button with the hope of seeing they kept the pigs is gone. Unlike winning (which always feels good even if it is only a handful of exp), losing experience is improved when you get a second chance gamble.
OK, when there is a Hive market for pigs without excessive fees, (1) is not so bad. The only excuse for (2) would be triggering this mode when one of the accounts in the game is new to give newcomers an opportunity to try the game for a fixed price before deciding if they want to buy the 10-15 pigs necessary for playing with the comfort of not thinking about a rebuy during every game (and lowering the tendency to fall in love with specific pig). Did I say "excuse"? That actually makes it a great idea.