On Saturday, 19 May 2018 10:36:18 UTC+1, Endulini wrote:
... the wireless for the convenience of installation

and inconvenience and cost of changing batteries in the detectors

and supposed ease of adding to it.

as long as the bits remain available and haven't been discontinued by the manufacturer. You also have a much smaller choice of detectors and accessories with wireless as each system is usually proprietary to its own manufacturer. Most wired systems are more-or-less standard so you can add eg safe limpets, artwork movement detectors, or appropriate smoke detectors [1], and outputs such as GSM diallers or smoke cloaks.

My main concern is the reliability in that my understanding
was that wireless systems are more susceptible to interference and
false-alarms - is this still the case?

Yes, for any wireless system likely to be considered for an ordinary domestic installation. High security wireless systems are available but will cost a lot more.

However, most ordinary wireless systems will probably be 'good enough' for domestic, unless you have a particular requirement for higher security.

[1] They won't comply with requirements for a fire detection system, but can be useful along with an autodialler to tell you your house is burning down when you're on holiday.

Owain