Aircooled VW owners have an assortment of options when choosing a distributor for their engine. If you only look on the surface it seems simple: The 'obvious' choice is the Bosch 009, right? Not necessarily. Once you do a little research, you'll find a variety of stock units (including the SVDA unit), as well as the Bosch 009, 010, and 050 series, and finally the Mallory, MSD and the Magneto. So which one is 'best'? Each of these units is excellent - for the right application.
For stock engines
For 34 PICT equipped engines
For modified engines, where no ignition fine tuning is desired
For engines with a relatively short connecting rod
For modified engines with a custom ignition curve, magnetic pickup, and that can be easily connected to a MSD ignition unit (5, 6AL, 7AL2/3, etc)
For the high tech junkie that wants infinite adjustability in their ignition timing
For engines with no battery or source of electricity (generator/alternator)