Just spoken to friendly local installer, and Clifford themselves (bolt and braces approach: I trust him implicity)
There is no such issue.
There was a problem on some STIs/WRXs a year ago which was down to the electrical environment of these cars being extrememly noisy. Clifford have issued a hardware fix for those that need it.
It will not damage your ECU, according to Clifford!
Get that fuelguard on ASAP, it's a really useful feature of the alarm!