Well the only discrepancy is that it seems like the Geforce 8000 series only supports 1.1 and I know for a fact that my 8800GS worked in SVP with hardware acceleration (as the wiki's GPU compatibility chart shows).
However the AMD and Intel GPUs on that same chart line up with their OpenCL 1.2 support, and this would also explain some of the results I've gotten. That is, SVP couldn't use an HD4670 but could use an HD5870 (on Windows), and the HD4670 only supports OpenCL 1.1 while the HD5870 supports OpenCL 1.2.
Additionally on modern Linux (anything newer than Ubuntu 14.04), any AMD GPU older than the GCN architecture is only supported via the mesa drivers. While mesa is very good nowadays, they are unfortunately still stuck on only OpenCL 1.1 support, resulting in things like my HD5870 being unable to be used by SVP (which leaves the HD5000 and HD6000 in a sort of no-mans-land with regards to GPGPU on Linux for the time being).