Have run two different electronic units in my Bug.
First was an Empi Accu-Fire unit and the second was a Compufire, both for the stock '74 single vacuum adv distributor. The Empi looked exactly the same as the Compufire unit except it didn't come in a box (it came in a simple clear plastic bag) and was missing the Compufire sticker. Installation was exactly the same.
The first unit lasted about a month before dying. I can't completely blame the unit... it died because the flat plastic disc that holds the magnets came loose and started grinding into the top of the unit (made from epoxy). It dug thru to the circuits below.
The flat disc fits over the cam lobes that the points ride on and under the rotor. One of the things that are not described in the instructions is that this disc raises the height of the rotor enough that you are required to grind off the bottom of the rotor. A few seconds w/ coarse sandpaper on a flat surface is enough. But if your grind off too much or don't square off the bottom, the disc can some loose and wobble. I believe this wobble caused the disc to grind into the top of the unit.
Once installed properly and having re-adjusted the timing, these little things keep reliable timing and lots of dwell time.
One other thing that I should mention. If your VW is old and you can't maintain a constant voltage to the coil when cranking you may have problems w/ electronic units. Remember that these things run off electricity. There is an extra 12v(+) lead from the unit that must be powered. In my case, a weak battery meant that the car would brank but wouldn't start. Less than 10v and I started having trouble. Yeah, I know, the problem is the battery, not the ignition. But given the choice of being able to start your car w/ 8v w/ points vs not being able to start w/ 9v w/ an electronic unit.... which do you think is more reliable?
Don't get me wrong... I run a Compufire unit, but I always keep a spare set of points and a condensor in the glove box along w/ a screwdriver and the tools to adjust the points/timing.... just in case!
AshMan40