Glad for the report that the inexpensive plates are working well. As for tightening, I don't think you should be too concerned. We haven't heard (on Birdforum) of socket failures on the ED50 since the design was changed (helicoil was replaced with a solid insert). Also, I am of the opinion that constant loosening/tightening/rattling around loose is probably more stressful than a consistent solidly tight (but not over-torqued) connection. That's one reason why I don't like a rubber interface--it inspires overtightening to prevent wiggling and loosening.
--AP
Thank you, Alexis, for this helpful and reassuring input.
In future, the plate will get tightened with the Allen key rather than by my fingers.