Regarding SQL Server Express Edition, it is limited in much more ways than just max database size (memory, buffer size, etc). Since SQL Server Developer Edition

Regarding SQL Server Express Edition, it is limited in much more ways than just max database size (memory, buffer size, etc). Since SQL Server Developer Edition become free most MSSQL developers I know switched to this one, as it has no limits whatsoever (except one - cannot be touched by end users). MSSQL Express seems more like a DB for small scale production environments now..