Well I don't thnk any are waterproof . Water resistent is more like it from what I've read . I use the garmin 2610. It comes with its own software don't no if it would work with yours or not . One way to get it working with the intercom is the Kennedy single set . Their are several different ones people on the board use and like . a search and some research on this one is what you need . Their are lots of options now that the 2610 doesn't have . good luck
Most of the 'common' motorcycle-friendly GPS units are rated to the same water-protection level: IPx7 which rates them for immersion in up to one meter of water for up to 30 minutes.
Most of these 'common' units can also support importing trip information from MS S&T but you'll need to use a 3rd-party conversion utility program.
That leaves your choice down to what other features do you need? Battery operation, etc.
You can review some of the options and pricing (including mounts & connectivity to the bike's audio system) with Rick's spreadsheet (assuming you can view an Excel file) http://www.rickandjanis.com/gps.htm