A lot of the "risk" is situational. So, LA vs NY vs Small Town somewhere... is all different. Also how, when, and where you lock the bike.

I'd hope your security guards would notice if someone starts chopping bikes off of the rack with an angle grinder. Of course, one trick is to look like one belongs.

Leaving your bike for 8 hours a day is also different than occasionally stopping at a grocery store for 15 minutes. As is leaving it anywhere outside overnight.

If you're mainly commuting to and from work, I'd ask the security guards if they would be offended if you leave a lock attached to the bike rack. That way you aren't lugging 20 pounds of lock back and forth every day. The spare lock & chain may come in handy.