I just did a conversion on one of my Kwikset locks from standard zwave to Zigbee over lunch. I bought the zigbee card off eBay, and it took about 30 seconds to swap out the zwave one.
While I'm primarily a zwave guy, this may convert me.
It paired in about 3 seconds (20 ft from hub), and reports status EVERY time the lock status changes manually, by code, or digitally (so far ).
Not sure how it will impact battery life yet. - I assume it will be somewhat lower, but we'll see.
Time will tell whether it says reliable on reporting/communication, but The initial experience is VERY positive!
SIDE NOTE - Zigbee locks apparently aren't affected by the bug introduced in 2.0.4 where zwave locks don't report lock code used. Codes are reported correct as-is in 2.0.4 with the zigbee lock.