The cylinder comes out, is that the main advantage?

Do you mean single cylinder deadbolts, so no key on the inside? 

I use the Kwikset SmartKey locks, and if you need to flip the keyhole on those all you have to do is pop the cylinder out, turn it 180 degrees, and re-insert it. 

Then they may work, but in larger buildings or complexes, you often need sub-masters (think of them as zoned masters).A lot of mechanical overhead (2 cylinders on one deadbolt) for a door lock.

It was one of those modern flappers that is a cylinder that goes up and down as opposed to the traditional flapper.  

If they don't follow through with that meeting I'd give whatever is proper notice in your state that I'll be changing the lock (hoping that they'll follow up and save me the expense/time -- I doubt you'll need to actually give notice for this).The next step would be to drill the lock, get the cylinder re-keyed, get the spares, put them in a lockbox at the unit and text/email the tenant the lockbox code.

A Toyota Tacoma, 4 cylinder, 4 wheel drive, 5 speed.

Many restaurants fail, some do okay, and then the ones that get the magic formula working on all cylinders do REALLY WELL. 

They did appear later that day in camouflage outfits & the youngest (last hired) guy got to go down the 20ft deep cylinder to pull the motors while 4 guys stood around, 2 covered in blood from a recent kill.

Those are pretty dreamy numbers even if the park was firing on all cylinders.