I had them as well before I upgraded to Ervocomm. They generally worked, but the breakdown rate was alarming, at least one in four games the receiver just wouldn't buzz when the button had been pressed. After experiment I found that wearing the receiver upside down on my arm made it more reliable, but even then it was hit and miss.
As an assistant they are a nightmare. Difficult to find the button, no idea if you've actually pressed it or not, and plain plastic handles that case the flag to go flying into orbit when you flag vigorously (some referees put tennis grips on the handle to stop this, but you shouldn't really need to).
I don't think there is a lot between Ervocomm and Touchline, but they are both miles ahead of RefsCall