YES

TRS:

  concat(leaf(),Y) -> Y
  concat(cons(U,V),Y) -> cons(U,concat(V,Y))
  lessleaves(X,leaf()) -> false()
  lessleaves(leaf(),cons(W,Z)) -> true()
  lessleaves(cons(U,V),cons(W,Z)) -> lessleaves(concat(U,V),concat(W,Z))

max/plus interpretations on N:

  concat_A(x1,x2) = max{0, 2 + x1, 1 + x2}
  concat#_A(x1,x2) = max{9, 1 + x1, 3}
  leaf_A = 1
  leaf#_A = 8
  cons_A(x1,x2) = max{9, 11 + x1, x2}
  cons#_A(x1,x2) = max{0, 2 + x1, 11}
  lessleaves_A(x1,x2) = max{0, 2, 1}
  lessleaves#_A(x1,x2) = max{4, 8, 6}
  false_A = 2
  false#_A = 5
  true_A = 2
  true#_A = 7

precedence:

  leaf = cons = lessleaves > concat = false = true