As tenants turn over, I'll be installing them on the rentals to eliminate lockout calls and so I don't have to rely on my giant key ring.I won't use them for apartments where the front door is right on the street because neighbors could watch my tenants enter the keypad code, for those I'll do it on the back door.

My first goal was to just reduce or eliminate my housing cost (rent/mortgage).

Contracter didn't get paid and recorded a document on the property which wasn't a lien but clouded it enough that it eliminated the possibility of an easy DIL.A borrower's "story" of his plan for a quick flip convinced me to lower my interest rate more than normal.

Up to you whether you eliminate them that say "yes".

Rental income appreciation = eliminates operating in red in 8 years (estimate)4.

If you can very specifically agree on what works and what does not, and put it in writing, it might eliminate some of the nail biting you seem to be experiencing already.  

"A reduction in force is a thoughtful and systematic elimination of positions.

Dodging these folks without follow through is a actually blessing in my view (they eliminated themselves from consideration automatically).. 

Finally I decided to do what the military had taught me for the previous 10 years - Circumvent the obstacle, Eliminate the Enemy, complete the mission!

The valve/hose unit sounds like a good idea in that it eliminates a potential leak point in the connection to the hose, but of course you're paying for that, and if either component goes the whole thing must be replaced.