Main concern is usually quality control. On previous cars, the ebay parts can be pretty decent, but still vary wildly depending on who the seller was, when you purchased, etc. It's kinda of luck of the draw. You should always due your due diligence to inspect the welds when the unit arrives, and possibly even give it a pressure test if you have the capability.
As oblivious stated, forum won't know for sure till we get a large sample size of a few dozen owners trying them out.
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