I think it should come down to a case by case basis, if someone is in jail for dealing ten pounds of cocaine, and then they get out of prison, I think that someday they should be able to get that off their record. If someone is convicted of a violent crime then I think it should stay on their record for much much longer, if forever.
I understand that people make mistakes and people can be driven to do some pretty crazy stuff, but not everyone should be able to get it off their record someday.
Maybe take it by a case by case basis, such as someone who are convicted of racketeering or dealing drugs should be able to get it off their record, but it should depend on the severity of the offense. While, as stated previously in this thread, if someone is convicted of murder, then it should never come off their record. It's a really difficult decision though.