We have been using a limited Z-wave network for about 3 years to support programmable entry at our facility. We use the Vera 2 Z-wave controller with schlage locks. I've posted elsewhere the limited condensation issue we've had with the older Schlage locks, but since that version is not available anymore, that's irrelevant.
Z-wave also creates a mesh network. My sense, using the Vera-2 controller, is we are applying a hobbyist setup to a business need. Vera-2 is adequate but not well engineered as a total solution. We update infrequently (whenever changing codes or fixing problems), and the user interface in not sufficiently intuitive that we can be proficient at 6-month use intervals. That means it's been something of a cost sink where a 10-minute code programming takes us an hour.
More recently Schlage and (someone else, don't remember who) have implemented their Nexia solution to Z-wave control. Although I have no experience with it, I would imagine that the consumer product is almost certainly more polished and useable. The older Schlage z-wave solution was web based and required a $5/month subscription. I understand a Nexia subscription is $10/month to enable web access.
More nodes = better performance (mesh network). If you have a challenge, plug an inexpensive zwave lamp module in an electrical outlet to cross mesh network gaps. We're managing 5 internal and external controlled access points across 1800 square feet, which has not been a problem for range.
Summary of our system:
It's adequate for what we do (doors with programmable entry codes)
Vera-2 user interface can be confusing, and it's sometimes challenging to do simple things that we do infrequently
I haven't noticed distance issues.
Schlage door handles support remote lock/unlock
Our schlage deadbolts support remote lock but not remote unlock, since a person must be standing there to manually disengage the deadbolt
That's my 2 cents worth
I'm also very interested in others' experience with an integrated centralized control environment. Because lighting control is desirable and easily retrofittable, we've toyed with the idea of z-waving most switched runs, but haven't done our homework. Since we've started with zwave, we'll probably continue with it, or do nothing.