This is a general response, naming attributes, based on your post and what I would want personally:-Monitored, police response -motion sensors in appropriate areas-cameras both indoor (public areas)  & outdoors - motion activated, records to cloud, holds for minimum 48 hours, w/ audio capability-remote light switch control-remote alarm mode settings : on, off, at home-remote lock / unlock entrance-remote doorbell camera (service, delivery interaction)-temperature & flood sensors around appropiate areas-alert capability (various) set for your concerns-ample exterior motion dection led lighting, some solar powered lights that illuminate all night-phone app that you are comfortable usingThere are more attributes I would want but I'll stop here. 

I think there are opportunities anywhere you live.As for bad neighborhood, I always invest in relatively bad neighborhood, that I will not like to live.However, that does not mean I am willing to invest to too low price market.If a large city has average sale price under replacement construction cost, that is an alarm to me.If one part of the city is low, but next neighborhood is way higher, I consider that an opportunity.You have to know the areas really well.I started buying REOs on the peninsula in 2009.

An alarm system is expensive for a short term use.We don't need any squatters moving in!  

The fact he had an issue with the late fee clause is alarming.

I test the smoke alarms, look for leaks, etc. 

Section 179 is expanded from $500k to $1mil and now includes certain improvements to non-residential properties: roofs, HVAC, alarms and security systems. 

I also told him to get an alarm - whatever the cop who took the report suggested to him (the PM had allegedly wrote down the name of the system, and would order it.)

When the SAM Smart Detector senses smoke, our central monitoring station automatically sends a text message to everyone on the contact list and our live operators call to see if it's a false alarm.

You need to change HVAC filters, check alarm batteries, check for leaking toilets, drains, taps etc. as well as for tenant caused damage.

I've done roofs, heating systems, monitored fire alarm systems, unit remodels, etc.