I believe that I have found a solution which does not require Google's intervention.
Like all of you, I was experiencing this problem and gave up months ago. Then about six weeks ago I made a small change within the settings of my GMail account and my contact photos have been "hi-res" ever since. Here's what I did:
http://screencast.com/t/MTE4N2Ji
By selecting "
Only show pictures that I've chosen for my contacts", it seems to have rendered the syncing one-way, phone-to-Google. I updated some of my photos with hi-res versions (using my phone's software). The photos were then changed on Google into low-res versions but not synced back to the phone.
I have modified and synced the aforementioned contacts multiple times from my phone and from Gmail with success, and the photos remained intact on the phone.
It has been six weeks, and everything works fine. I can't guarantee that this will work for you or that it will continue to work for me, but for the moment now it appears to function flawlessly. If you try this, I would suggest starting off with just a few photos and work your way up as you become more confident that the syncing will continue to operate in this manner.
The only minor downside to this is that if you have friends that update their photo on their Google Account / Gmail, you will no longer be able to see those updated images in Google Talk or your phone as they will be replaced by the photo you chose for them from your phone. That's no big problem for me as I prefer hi-res photos of my friends to a pixelated avatar of a panda hugging a lizard any day of the week, however I can understand how that may discourage some from applying this method.
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