Anyway, I didn't intend sto sound negative, it's just something I genuinely don't understand.
As for the Raspberry Pi, I'm not sure I agree 100% with your comment. The GPU on the Raspi SoC is actually quite powerful, it should actually be in the same ballpark as the 16 core Parallella (the Raspi GPU is quoted with a (yeah, mythical) theoretical peak performance of ca 24 GFLOPS (!!) single precision).
Having said that, the Raspi GPU is not intended for general purpose computing, and that's where the Parallella shines and is innovative, and that's the reason I backed the project and have not regretted it.
The one none-graphics application that AFAIK has been implemented on the Raspberry Pi GPU so far is FFT.
My personal goal is to make an accelerated version of the EInstein@Home "Binary Pulsar Search" app that needs a length 3*2^22 real-to-complex FFT for both the Raspi and the Parallella.
At the moment I am quite sure the Raspi GPU will beat the 16 core Epiphany. If anyone thinks he/she can do a 3*2^22 real-to-complex FFT (single precision) faster on the Parallella than the fatest version using the RaspiPi's GPU, please let me know. I might be willing to make a formal bet out of it, with (say) a crate of beer as the prize

Cheers
HBE