OK...
Installed the custom build of SmarterMail (5.5.3393) and tried syncing with two versions of Funambol Blackberry Client.
v7.0.7 - No changes from 5.5.3362 - fields such as email and DOB don't transfer across. 2nd line of address still being lost (though I'm not sure if this is SmarterMail's fault, or if BlackBerry's aren't fully compliant with the SyncML standards in having 2 address line fileds).
v7.2.3 - Email addresses now carrying across. No longer have the work phone/fax confusion that was happening with 5.5.3362. Wierd thing though - the DOB field on all contacts gets set to the date of the synchronisation (irrespective of whether the contact on the phone had a DOB assigned to the contact).
Still some gremlins to sort out it would seem. Can't safely enable 2-way sync of contacts and calendars as I'd ideally like between my Blackberry and SmarterMail while the contact data is getting morphed on the way through.
Hope this feedback helps them come closer to a solution.
If you're liasing with the guys at ST, feel free to let them know that I'm happy to act as a tester for them in working out this problem (in fact I'd be happy to beta test any of their upcoming products come to think of it - glad to help them make an excellent set of products even more polished!)...
Cheers,
-Ben