Memo data is located in an entirely different application: Mark/Space MemoPad. You should see that all of your memo data has been been transferred from your organizer to that application by the Mark/Space Memos conduit.
Aside from the missing memos, what specifically constitutes 'incomplete?' Some data may not transfer properly due to limitations of both the Palm OS PIM applications and the Sync Services framework but, without access to your data, I have no idea specifically what these issues are. Are you missing the contents of some fields, such as addresses, electronic mail address or IM identifiers?
You should read
this document to determine if mapping issues interfere with the transfer of event data, and
this one to determine if they interfere with the transfer of contact data.
Wether or not the Palm Desktop is installed or not—and has data records associated with it or not—is immaterial. You should not delete it if there is every any possibility that you will later choose to revert to using iSync and the iSync Palm Conduit, because some components of the Palm Desktop are required to support them, and reinstalling the Palm Desktop can create additional issues which are simply to complex to describe here.
DO NOT delete the contact records now in your Address Book or the event or task records in iCal unless you plan to once again overwrite them during the next event, because to do so will trigger their removal during a standard synchronization event. That's not an issue with the way that the Missing Sync for Palm OS operates - it is a foundational behavior of the Sync Services framework.