The only problem with most copper aftermarket evaps is that they are crudely made and don't fit. We have installed many but don't anymore as they often require severe butchering of the evap case to get them inside. The biggest problem with this is that you will never know untill you are sitting there with it all apart and you planned to drive the car the next day. You will be forced to accept less than your standard to procede.
The units with valves usually don't have this problem
Bosch Master, ASE Master, L1
33 years MB technician