The biggest issue I see is if that laptop may move from place to place and you would still want access. With RDP you would have to configure the connected router for every location where the laptop is connected. That's not going to work very well if it's sitting in a hotel room somewhere and you can't do that. (It's still not convenient to do port forwarding on any router.)
Logmein works regardless of what kind of connection the latop has or where it's located. Logmein will also reconfigure itself based on the iPad or Laptop connection speed. The laptop communicates with the Logmein service and then when you need to connect Logmein tells you what it takes to get to the laptop. You can also sit down in front of any PC or Mac browser and use logmein from there without the need for any special program.