Eh I consider it something of a sunk cost fallacy. If the system is so flawed and easily broken that most any spellcaster class can render non-spellcasters superfluous it's better to find a less poorly thought out system, even if you already have experience and splats for 3.5. My GM got started on 3/3.5 like a ton of people but he's been willing to try out other systems. About the only thing we've discarded off-hand has been RIFTs because dear lord that's a clusterfuck.

Anyway, enough about me and my dislike over 3.5, which characters are returning? Or did you mean relative character ages and experience levels?