You've literally tested it on a single file, enwik8. That's not enough to extrapolate valuable results. One of the benchmarks:

  time ./bsc e ../linux.tar linux.bsc -e2 -b16 -T
  68.69s user 1.14s system 99% cpu 117M memory 1:09.84 total

While bzip3 uses 98M, takes 1min 17s to produce a 129023171 byte file, compared to 127747834B from BSC. They're very similar except bzip3 tends to use less memory and decompresses a little slower. BSC is much more mature than bzip3 though, and the benchmarks might be a subject to change some time in the future. Surprisingly, BSC code isn't really that robust (I reported a UB bug to libsais and had to pretty much rework the LZP code because it couldn't stand fuzzing).