Most people have a bias against Diners because it isn't accepted as widely as Amex, and certainly not as ubiquitous as Visa or Mastercard. But this is not the case in much of the world outside of North America, and if you use it to buy airline tickets or stay at major hotel chains, this is not a drawback. The insurance features are excellent, though you can top up the INGLE Health plan that all Aeroplan members have [which you will likely get info on soon]. Lounges have always been useful, again when travelling in certain countries, and they don't charge for alcohol. Yes, not many in North America, but the card was designed for real international travellers. As you say, this is a no-brainer!