The QE is an invaluable hive management tool.
No, they are not all the same. Asian strain Cerana bees are smaller, and thusly so are their QE equipment being sold. Also the size of comb, foundation, you use determines to some extent the size of your bees. Eg: My heavy haulers do not fit through those basic cheap plastic QE?s. Also newbees be aware that some propolis mats are erroneously marketed as QE.
If you want to buy the right ones, want to buy once, then invest in Steel only and buy them only from a reputable supplier local to you. The bees flow through a proper quality steel QE like it is not there at all. Except the queen, of course.
Imho.