I had a road angel before but much prefer the S4. Compact, great bright display (that sits on the scuttle and doubles as a speedo), seems to get all the traps, configurable, plugs into my Autocom and has a human voice to tell you what type of trap is coming and what speed you should be doing. Means you don't need to take your eyes off the road.
Can't recommend it more highly and got it very cheap at Maplin (even cheaper if you use the £15 off voucher in the catalogue).
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Superlight R #41