If we're going for maximum annoyance value, from the technical end, it would also make sense that once the character has attained sufficient xp in the new level to regain the previous classes abilities, the character would then progress as a multi-classed character as opposed to a dual-classed one. If they're using skills from both pools, they should progress in both classes. I could see getting a little rusty in the first class, so being forced to resume that one at 1 level less than previously attained.
Just an opinion, folks.
Edited by berelinde, 01 August 2006 - 03:43 AM.