Not sure what you're doing there; I have tens of thousands of kilometers on PD-R540s and DA7800 pedals, both of which have plastic plates. None of them have ever broken or been ruined in any way.
But hey, spend your money any way you like.
No problem. I bought them once, learned what was ****ty about them, and moved on to something better for a little bit more in $. I learned from my mistake. Wiser people will learn from the mistakes of others. If I knew then what I know now, I would have saved the price of R540s.
BUT don't take my word for it.....a quick google will explain all you need to know....
Shimano PD-R540 Pedals and silly plastic bits
http://craig.mcgregor.gen.nz/2011/06...and-silly.html