No. This is not accurate. The difference is usually a 8-10dBm spread. It's only at the maximum threshold of the GS3 is the data unusable. In our testing, when the EVO LTE would give up the signal, the GS3 was still performing 4-6Mbps download. It is just that the GS3 will stick to the signal all the way down to zero.
In our observations, the GS3 would not stick to a signal all the way to zero download, but would drop to as low as zero upload. The differences the poster noted above could be related to the servers being used in his testing. We varied our testing to several servers and took averages.
The extra usability beyond where the EVO LTE gives up its LTE signal is significant. And it is not just the GS3 that out performs the EVO, it's also the LG Viper, Galaxy Nexus, Photon Q and now the iPhone. Do not underestimate the EVO's LTE connectivity issue. It is indeed giving up much usable LTE coverage.
Robert