View 5 is supported on 4.1 update 1 so you don't have to upgrade. There are certain features that would only be available in vSphere 5 so you would have to upgrade if there is something you were looking to utilize. Here is a link to the VMware Interoperability Guide, http://partnerweb.vmware.com/comp_guide2/sim/interop_matrix.php
here is a KB for moving the SQL database, http://kb.vmware.com/kb/7960893. The last time I did it I felt the procedure was fairly simple.
It shouldn't change any VMID or anything.