How to get handheld to overwrite computer

Question

I'm considering the switch from my Palm Desktop to iCal but I noticed when setting the iSync up that it doesn't allow me to choose handheld overwrites computer.
1)What does it mean when I select merge data on computer and device? Seems I may end up with duplicates if the information isn't exactly entered the same. For example, if I used a lower case letter instead of an upper case in some fields.
2)The point is that I make changes on my Palm every day and I want those changes reflected in iCal. I want to ensure that what's on the handheld overwrites the computer.
4) I've read there's problems with fields not matching up. Am I just better off not making the switch?
3)What advantage is there to using the Missing Sync program?

Answer 1

The Sync Services framework, under which both iSync and the Missing Sync for Palm OS operate, has no provision equivalent to Palm's Handheld overwrites Macintosh conduit setting. That options simply is not supported under Mac OS X 10.4, though changes to the framework under Mac OS X 10.5 may provide such support.
To merge means to equate records at the field level. If iSync is unable to resolve the differences between records at the field level—using the Conflict Manager—then you will be asked to resolve them by picking one of two conflicting records to replace the other in the truth database, in which case that selected records will be pulled from it to other registered sync clients. Such differences as capitalization do not generally trigger this mechanism, though it is a good idea to enter data consistently. Such differences will not cause record duplication.
I should pause here to explain that it's not actually about the differences between the records stored in any application, device or server: all records which reside there are actually pulled from the truth database, a centralized single source of synchronization data which is invisible to you as a user. Each client pulls data from and pushes changes to this database, with the exception of iTunes, which cannot pull changes from an iPod, which is effectively a write-only device. Devices do not directly interact with each other. They interact only with the truth database.
Here is a link to a document which explains this behavior:
http://developer.apple.com/macosx/syncservices.html
Synchronization is not about overwriting data unidirectionally. It is about reflecting the additions, deletions or modifications to records made anywhere, everywhere, at the conclusion of a session.
It's not so much that fields don't match up, as it is that shortcomings in field mapping in the iSync Palm Conduit leave your data out of the process if, for example, an address is labeled something other than 'home.' If it's labeled 'work' or 'other' or you've selected a custom label, iSync and the iSync Palm Conduit ignore it.
This is not the case with the Missing Sync for Palm OS, which supports extended field labels, categories for contacts and calendars, contact photographs or icons, calendar colors, the synchronization of multiple electronic mail address, an IM address and a web URL in each record, with what are generally termed 'advanced' Palm devices: those running Palm OS 5.2 or later, including all currently offered Palm handheld organizers and smartphones.
The Missing Sync for Palm OS also includes conduits to synchronize AvantGo content, non-AAC protected media files with iTunes and images with iPhoto, a conduit and matching OS X application to synchronize memos, and simple device to computer time synchronization. None of these are supported by iSync. The Missing Sync allows you to configure conduit sets and group them as to synchronization interface - Bluetooth, or USB, for example. For WiFi enabled Palm devices, synchronization via WiFi is supported.
More information about the Missing Sync or Palm OS is available here:
http://www.markspace.com/missingsync_palmos.php