I am getting requests to design BS8629 systems all over the place at the moment - normally with the caveat that they are to be a temporary fire alarm system to reduce waking watch and then repurposed to an Evacuation system to BS8629 afterwards, leaving the detection in to benefit the occupants.
That is easy, and is instantly fodder for the wastepaper bin, as it is clearly a waste of time and a knee jerk reaction from people who are unaware of the requirements.
However In regards to recommending them as part of a FRA, I would refer to 4.2b of the standard, which states:
....any proposal to install an evacuation alert system for use by the fire and rescue service should be subject to consultation with the fire and rescue service before proceeding with the design of the system.
As I say, I am getting requests to design them, but truth be known, I rarely do. I wish I could charge for not doing stuff!