While investigating how to set up YAFU for myself, I discovered that a couple of the apps it uses have CUDA versions. So, might it be possible to create a version of YAFU that uses CUDA?

The easiest way I can think of to set it up would be, after running some small ECM tests on the CPU, to run bigger ECM tests on the GPU while running NFS on the CPU, and let the first algorithm to find a factor win. A slightly more complicated way would be to do initial ECM tests on the CPU while finding NFS polynomials on the GPU, and then switch (to ECM on the GPU and the rest of NFS on the CPU).