Well you my friend have a battle around personal liable or company liable on your hands. What is the direction your company wants to proceed with? I guess if you don't have major security concerns and have to worry about NPI data BES might be overkill.
Outside of the major security / management aspect BES does provide a number of nice features for the end user:
Remote email lookup
Wireless reconcile / purge deleted items
Global address lookup
VPN access to internal websites via MDS
View calendar free/busy
Also from the management end you get full asset reporting and if the company foots the bill you can do user modeling to profile their usage (low, med, heavy) so you can prove out your ROI.