Good idea, Glen. I have a Link ECU and my son is learning on Raspberry Pi to interpret the CAN bus data.
I have asked him to put in audible alarm for temp, will add "loss of coolant pressure" to the requirements :-).
Where are you fitting your pressure sensor ?
 
My stock 3sgte is very early and Falcon mentioned that the coolant system was revised. Hopefully my cooling is adequate for shortish sessions on track days. 

I was going to put it in the main hose that comes off of the cooling neck above the gearbox. 
Using a Raspberry Pi to trigger an alarm or a light is a good idea. I recommend a light instead of an alarm because you may not hear it when you are wearing a helmet and the engine is at WOT and 7000rpm 😎😎😎 
As long as your radiator is good, you will be fine. 
I used the large Mishimoto radiator for a long time until it cracked, and I am now using a standard size Fenix radiator. It was very cheap, and I'm happy with it.
If you are worried about cooling and have an old radiator, I highly recommend replacing it with a new one like the Fenix.
I used the Fenix at Mount Panorama last year and the engine didn't overheat even though the ambient temperature was in the mid 30's.

My radiator is ok, been serviced by a radiator guy. My concern is the small/slow leak of coolant suddenly dumping it all. A flashing light is also a good idea. Since it is interpreting ECU data, instead of advising the driver, it could simply pull some boost and ignition timing. I think the original TVIS did that.

Yes that's what Haltech Elite and other ECUs do. They call it engine protection.
I have a Link G4+ in my GT4 though don't recall seeing any engine protection features. It doesn't mean they aren't there though.