Is there a way to run a traffic report in a Mitel SX2000 environment that will allow me to see the number of calls that overflow to voice mail from our main (receptionist manned) line? This location has 4 each 1000 Mitel attendant stations that intercept all calls to our main number/line.  

Does your SX2K have the "Traffic Reporting" package (MSA-A-08)?

If so you can do hourly (or half-hourly or quarter-hourly) reports on your attendants and attendant groups.
Simply start a CDE session and edit the Traffic Options Assignment form to define the hours and scope of what you want to monitor; included can be trunks, trunk groups, routes, route lists, attendants, attendant groups, etc, etc.
Note: Setting too many options can result in very copious amounts of output.

Once set up it will not begin working until the next time the period becomes active (if you set the start time for a time earlier than it is right now it will not start until tomorrow at that time)

This will give you a great deal of very useful data when trying to 'right-size' your attendant operation and identify which of your attendants is most productive and who isn't carrying their share of the load.

It's a pretty basic data dump which you can set up to go to any LPR port either set for autoprint or on demand.

Tip: don't even think of sending your traffic reports to LPR3