YES

TRS:

  dfib(s(s(x)),y) -> dfib(s(x),dfib(x,y))

max/plus interpretations on N:

  dfib_A(x1,x2) = max{1, 1 + x1, x2}
  dfib#_A(x1,x2) = max{1, 1 + x1, x2}
  s_A(x1) = max{0, 1 + x1}
  s#_A(x1) = max{0, 1 + x1}

precedence:

  dfib > s