Hazards of Upgrading SQL Server Express 2008 to R2 A client of mine reached the 4GB database limit on a SQL Server 2008 Express.
As a test I installed the R2 version on another machine and restored a backup of the database.

I'd like to upgrade the actual server itself, though I'm worried about what any of the pitfalls/consequences could be in addition to compromising the system stability.

This is because, additional critical applications (including an ERP I don't fully understand) are running on this machine which would require calling another company to re-install/setup.

I've given the client 3 options:


Get new hardware in order to host the R2 server there (independent of current server).
Use current setup that was a test.
Take the risk and install the update to R2 on the actual server risking the 5% (or however much it is) risk of anything in the system going unstable.


I've also thought about cloning the whole computer using clonzilla (ghost) etc, but as I'm supporting remotely this would require I travel ~ 500km. 

Also, this is a serious problem as they cannot add new records to this database.
You're unlikely to run into any issues with this but that said, it's rarely caution that gets a DBA fired. 

I'd probably go with installing a named instance, side-by-side with the existing instance. As you've got a test bed server up already I'd also suggest testing the application with 2012 Express. Why upgrade to an already out-dated version?