Diablo III - Official Discussion Thread - Who will beat Inferno first?

[IllegalPaladin]

Your progression can be destroyed if you play with friends who are higher level.

I joined my friend's party while I was still in Act 1 and found myself viewing the Act 4 cutscene, pop up in the Act 4 hub town and was even able to join the fight of an Act 4 boss (and was killed in one hit)