Every D&D game I've played in where I've lost a character (read: all of them), the DM had me roll up as same level as the party. Then again, the main DM I played under was notably sadistic, so if everyone had to roll a level under the lowest player, we would all soon be lower level than the encounter we were playing.
That said, I'll admit to fully taking advantage of the 100% xp rollover on TR. I don't always use all of the xp up front, but it lets me start at a level I'm comfortable with being at while still leaving me a cache of xp I can dip into if I realize I forgot something or need to pick up something quick to cover whatever it is that needs doing at the moment.