I didn't mean promoting (though thanks for the info on that too), but rather a horizontal class change, that is switching from one Tier 1 class to a different Tier 1 class. Like...going from a Fighter to a Wyvern Rider. If it's too much of a complication or impossible to do, that's perfectly fine, I was just wondering.

Edit: Oh, also, is it still going to be more efficient for us to promote at Lvl 20 instead of at Lvl 10?