I think the principle of interlocking the breakers so you can't back feed the grid is sound. You would have evaluate each product to decide whether you believe the execution is done properly. I think if it is sold by the OEM it should be OK. For a residential application where automatic switching is not required this may be the easiest option. Just be sure the O/C device selected for the generator side is sized properly and the actual installation of the interlock is done per manufacturer spec. You could still run into a 110.3(B) problem if the panel manufacturer says a 3d party model is not equal to their device (like the challenger breaker problem). I suppose when 3d party interlocks start competing with the panel manufacturer's model in any significant way we will hear about this one.
