For reference, BC1 non-perceptual gets ~36.92 dB on this test set, so even just mode 6 BC7 (the first data points on the bottom left) is superior to BC1's quality.
Basis non-RDO BC7 also has a "ultra" profile which is ~.49 dB better than ispc_texcomp's slow profile (its highest quality mode), but you pay a steep price in encoding time (959 secs vs. ~350 secs for ispc_texcomp's slow profile). In this mode Basis is even better than the reference BC7 encoder in NVidia's NVTT (but we're ridiculously faster):
Basis BC7 ultra: 953.2 secs 47.255552 dB
Basis BC7 slow: 365.5 secs 47.162389 dB
NVTT: 28061.9 secs 47.141580 dB
ispc_texcomp slow: 353.6 secs 46.769749 dB
The leftmost bottom samples are mode 6 only (ispc_texcomp's ultrafast profile). We are 19% faster at slightly higher quality here.
Basis non-RDO BC7 supports a powerful perceptual mode which I'll benchmark tomorrow. In this mode we kinda wreck ispc_texcomp at the same Luma PSNR (but to be fair ispc_texcomp doesn't support a perceptual mode at all, which is a serious deficiency).