The instructions for the push in connectors I have seen disallow their use with aluminum wire. This makes sense because push in (stab in connections) have always been against code for aluminum wire.

I have done rework in a house where the make up was done using these type of connectors. It seems to make for a neat installation. I did not see any failures. This house is about 15 years old. I would like to know if anyone has seen problems with feed through loads using them.