The reference implementation of SRFI 66 has a small bug:  The definition
of u8vector=? has:

  (and (= (u8vector-ref u8vector-1)
          (u8vector-ref u8vector-2))

which should read (I believe):

  (and (= (u8vector-ref u8vector-1 i)
          (u8vector-ref u8vector-2 i))

[I realize the above may be of limited interest given support for
bytevectors in R7RS, etc.  I came across the bug I was porting some
older code which used this SRFI's procedures.]

Regards,

-chaw