I tossed your first two benchmarks into a spreadsheet.
Average 1% performance increase by running in SATA3 mode - not bad.
I suspect that a more modern drive that can push around 200MB/sec sequential would have a larger performance difference - but someone that owns one would have to run the benchmarks to find out for sure.
I didn't include the File Benchmarks because without exact numbers it's hard to be accurate. But looking at this 32K File Benchmark, it's easy to see the difference is far larger than 1%.
With the smaller File Benchmarks, what you are seeing is the effect of cache - the reads sit in cache, enabling the drive to perform very close to SATA2 or SATA3's theoretical limits. That's the reason you can get results like this out of somewhat slow 64MB cache 'Green' drives.
Knocks the socks off an SSD, right? No, not really. As soon as you bump up the size of the test set, you get more realistic numbers:
In your benchmarks once you reach 64MB test size the performance difference starts to diminish, because the drive doesn't have enough cache for the entire benchmark file. In the 512MB benchmark we can see that SATA2 vs SATA3 is very close, slightly favouring SATA3.
Small file benchmarks don't tell us much about real world performance, but there are a few select tasks that they may apply to - the autosave feature in Office, for example. If you're reading or saving the same file over and over, you're going to get the speed you see in in the smaller File Benchmarks. But most of the time the first two benchmarks in this thread are probably more relevant.