We use Lockitron on our offices and it has saved us a lot of trouble. Empirically people are a lot less likely to forget their phone than to forget keys, presumably because you use your phone for so many other things whereas most keys do nothing but get you into a single building.
"Empirically people are a lot less likely to forget their phone than to forget keys," That also varies on whether you drive a car or take public transportation. If you drive, leaving your house requires taking your keys and it becomes a habit. Same with leaving work. If you drove there you need your keys to leave. A good way around forgetting keys also is a realtor style lockbox either on the door or hidden with a sp…
I ALWAYS have my phone though. Quite frankly, I look forward to the day when my phone replaces my access badge/key-card at work.
Of course there is the arguement "but someone could take your phone and access the MDF!" -- well they can always steal my access badge as well.
I have forgotten my badge countless times in my career though I have forgotten my phone all of once.