I agree with you grimbletart that it's difficult to compare eras because of the changes in the game.
I wasn't fortunate enough to see Rod Laver play, but I agree with you that he was an amazing player, certainly by far the best of his own era. I think he has many similarities to Nadal, being a lefty, employing a lot of whipping top spin & with an outstanding touch at the net.
I think given his height and physique Laver might have struggled against the giants of today's game. He would also have had to adapt his natural attacking serve/volley style which is a dying art in today's game. That's another reason it's hard to compare eras, because the changes in technology have bred a completely different type of player.