A few people complain about Suunto and UWATEC computers keep losing transmissions underwater. Not too many people complain about Oceanic/Aeris computers losing transmissions.
Take that for what it is. It's not like there's a true set of statistics to go by.
I have two Uwatecs - a SmartTEC and a Galileo Sol. I also have a friend who's had his for a year.
Uwatec rarely actually loses the transmission . . . in fact, it hasn't happened to me at all . . . If "losing" is where the computer displays "---" instead of the psi.
What it does do is lose connectivity for a second or two . . . and it complains. I've only had that happen when the transmitter battery is nearing its end . . . the "replace trans battery" warning came on after that dive. The audible warning is annoying. However, easily fixed by replacing the transmitter battery.