hold up devices are 24/7 so system doesn't need to be set for them to work.
Loud noises can be off putting, so can smoke screens, but it comes down to the risk versus cost and if your going to that effort then considering a monitored system is sensible, but that's a recurring costs rather than a one off cost for equipment. Remember though a response from burglary to attendance on site can be some time.
an inferno sounder is capable of making the intruders suffer. that said it isn't cheap, and other internal sounders whilst not as disabling can make it difficult for them to communicate. a smoke screen makes it difficult to see.
so you can have a duress code, if the system was set and you were forced to disarm the system, the alarm is disarmed and the duress notification goes out, as its duress its silent, you could then have your PA device on audible.
Again Bernard makes a point of two different types of burglaries but its isn't as simple as that but it does make a good point none the less.
If your talking of being held up, then you are a high risk candidate and you should look at what you do as a result.
Most burglars (low risk) will leave the building immediately upon being disturbed (most common), high risk they may be willing to use violence.
That said high risk violent burglars is not so common.
As for reminders to set, there are ways of doing this, simple ones and more complicated ones depending on the system you have and whats free on it. Those using apps can login in and see on there phone if the system is armed or not, also the Texecom connect app you can have a PA button on your phone too.
I am still of the opinion you should get a quotation from someone local and ask for their opinion based on your exact needs, getting a quote doesn't oblige you to take up that system but may help you decide what you want/ need.