You're protected on both the computer and phone end while you're playing with contact syncing. I just went through this, and you can restore your contacts on google/gmail on the computer end if you accidentally delete a few, with a pretty flexible time frame choice. And if you've exported your contacts on your phone, you have a file with all of those. The way that I just dealt with this was:
1. If your google account syncing is turned on, turn it off on your phone for the duration of doing all the steps below.
2. Clean up your contacts in google...I had about 300, and ended up with a lot less that I actually use when I was done doing this. This obviously isn't mandatory, it just lightens your load a bit *smile*.
3. Make sure that the contacts on your phone are also in your google contact list. You can do this by carefully merging that export file that you created on your phone into your google contacts.and avoid dpulicates. This is using the "import" function in google contacts.
4. Make sure that only the contacts that you want to see on your phone have phone numbers in them in your google contacts.
4. Once you have your google contacts set up the way that you want them, delete all the contacts on your phone (remember that you have them backed up).
5. Go to your google account on your phone in "settings" and press "sync contacts".
6. All your google contacts should now be in your contacts app on your phone.
7. While in your "contacts" app, use the Menu key to bring up "settings" there, and turn on "show only contacts with phone numbers".
8. Now the only contacts that you see in your "contacts" app on your phone should be those with phone numbers, and you can now sync contacts when you need to and things should be fine since you have the same contacts on your phone as in google contacts.
At this point, you can again back up your contacts on your phone if you want (export) and it will not overwrite any previous exports, since the file names created are serialized. Just in case something goes wrong. You can also use the export file on your phone to import into google contacts, should you need to do that. When you do an import into google contacts, it creates a group for that import, rather than immediately merging them into your contacts list, and you can merge them when you're ready, if you want to.
Pretty flexible interface. The only part that I really object to is having to have all those google contacts on my phone, even though only the ones with phone numbers are displayed. But I'm sure in the scheme of the 16GB. on my phone, that's not a very large piece. And the results are simple, initially identical contact lists on your phone and in google contacts, and you can go from there.