After trying maybe a dozen different GPS camera detection options over the years, the two main criteria for me are as follows:
1. Is the database good? However good the hardware is, it'll be useless if the database isn't accurate and up to date. The databases largely rely on crowd-sourcing for their data, and since there isn't a single dominant database provider for the whole of Europe, it's an important consideration. For example, I've found the PGPSW database to be the best in the UK, however it's relatively weak in other European countries (where it doesn't have many users). Conversely, in France and Belgium, Coyote is by far and away the market leader. In Germany, POIbase is very strong. As most of you guys are in the UK, I'd recommend the PGPSW database, since it works well in the UK, and it doesn't matter if you get flashed in France, Belgium, or anywhere else for that matter. The UK doesn't share number-plate data with other countries. For myself, the UK doesn't matter, but both France and the Netherlands have reciprocal agreements with Belgium, so I need to make sure those three countries are well covered.
2. Is the hardware configurable? Some basic units will report all cameras, regardless of the direction of travel. I recently bought POIbase's own-model unit, and it isn't configurable at all. The beep is far too loud (and can't be changed in either tone or volume), to the extent that I end up switching it off. It sounds when 500m from a camera, regardless of speed. On motorways, this can be too little, in slow-moving town traffic, it can be an eternity of ear-piercing beeps! Many years ago I bought the Inforad unit the OP mentioned. It would be unfair of me to dismiss it, as I can't really remember much about it. However, the fact that it only stayed in my car for a couple of days before being chucked in the box in the attic (you know, the one with all the old mobiles, laptop chargers, USB cables and so on) means that I couldn't get along with it for some reason.
The best options I've found so far are smartphone apps, which tend to be very configurable (warnings based on time instead of distance, different alert sounds and volume...). However, I want an always-on solution and these apps kill your battery life, not to mention warming up your phone (and whatever is next to it when in your pocket!). I may end up buying a cheap/second-hand smartphone just to leave plugged in inside the car.
