Electronic or UV? Never had much luck with either one to tell you the truth.
I found searching for leaks in domestic sealed systems to time consuming and only did it back when I was doing warranty work.
HVAC and other commercial refrigeration systems I can see searching for leaks, as they cost more to start with and it's not simply a matter of carting in a new unit and plugging it in.
In either case I never like purchasing cheap equipment, but that's just me.