UPDATE: The folks at Supernova agree that it is probably the capacitor.
They gave me a couple of options for the replacement -
Option 1: standard warranty replacement, where I send the light to Germany and they send a new one to me. I'd have to pay shipping to Germany (is this typical for warranty replacements?)
Option 2: I keep the current light, and they will send me a new one for 58 Euros ($75-$78).

Seems like a no brainer to me. The existing light works great - it is just the standlight and tail light circuit that is buggered. Plus I'd probably spend at least $20-$25 for one way shipping (with some form of expediency) plus any premium on the standard shipping that the factory uses (to get the replacement to me quickly, since I'd be without a reliable light).

So, for a grand total of $190 for the original light plus $77 ($265) I'll have two lights. Cool. I've been wanting to get my wife set up with a dynamo light.