Mr Arthur ( retired fireman on here occasionally ) fitted on to his A 10 about 10 years ago.
The only real problem with it had been the fact all the other noises that the primary hid became apparent.
That bike has done 8 BSA National Rallies ridden all the way from Coffs Harbour to the various locations , including Claire , Norriopta , Torquay , Goulburn & Cowra .
Lots of these were better than 2000 mile round trips carrying a big load of camping gear.
So yes they work really well.
Weather they are worth the price is a matter of personal choice.