The big difference between the Beo4 (162x) and the Beo4 (1710) is the so called Navigation button, which is like a little joystick to move Up, Down, Left, Right. It replaces the GO button from the 162x and features a Select functionality, too. Other than that the 1710 has a new button layout (e.g. Play and Back button).
As a general customer I wouldn't see a reason not to choose the newer remote, however, I think it is appropriate to warn you that the 1710 doesn't support all PUC files yet. So if you control your 3rd party boxes with PUC you should be sure that all of them are compatible with the 1710.