A bit more poking about in the new Cortex v21 reveals some new modules on the way.
There's some new combinations of sensory modules, for example the PLH, combining PIR, Light Level, Temperature and Humidity in a single module. It's not listed on the Idratek website, but another new combo, the PTH (PIR, Temp, Humidity) is.
The PLH looks like a great combination. If you go with my scheme of IR, Temp+Humidity and PIR+ Light Level all ceiling mounted this allows you to bring the module down to 2, ie it can be fitted using a standard twin-gang dry lining box, much easier to fit than arranging 2+1 or 3 single gangs.
I don't know the price, but I guess that it offers a saving in that regard as well.
The complete list of new modules:
DFP (Display Panel)
PTH (PIR, Temp, Humidity)
LTS (Light, Temp)
LTH (Light, Temp. Humidity)
PLT (PIR, Light, Temp)
PLH (PIR, Light, Temp, Humidity)