After much thought, I finally bought the JMCB2003-DU. The folks at Sierra (not BMW in Nevada, although they're upstanding too) were very nice. Now I'm getting my nerve up to installing the thing. It should arrive in time for a weekend project. That is, if no babies have the nerve to get sick this weekend when I'm on call. Any words of wisdom would be appreciated from anybody who has installed this on their own bike.