Guys, my PS3 YLOD around 3 months before GT5 came out, I did extensive research and have done both the restore on the same PS3 unit and the data transfer between different (my old and new) PS3s. So, I'm positive by personal experience and a lot of research that what I posted up there is 100% accurate.
I've done it several times and I lost absolutely no info.
Don't worry, the only scenario where you would lose your data is if you tried to restore your PS3's back up to a
different PS3. If you do a back up and restore to the same PS3 or do a data transfer utility to a new one, you'll keep your GT5 data.