MC cartridges and metal platters

I have read you should not use a MC cartridge with a turntable which has a metal platter, and Music Hall strongly recommends not to do so, at least on their Music Hall 2.2. However, every single HIFI dealer I have talked to disagrees and state they have done this countless times without problems. What is the truth?. 
To be specific MC cartridges should not be used with magnetically permeable platters, such as those made of iron, however almost all current turntables with metal platters have them made of aluminum which poses no likelihood of attraction to the magnets in an MC cartridge.
Thanks so much; mystery finally solved!
What about Thorens zinc alloy composition platters, Viridian?Needless to say, I've forgotten my college chemistry.
Remove your MC cartridge and place it on the side of the platter. If it sticks, don't use it. Send it to me.
The one I recall has iron platter is QRK. 

 Boofer, the Thorens TD124 has an iron platter and it can be problematic with some MCs. Of course, there is an aluminum topper, which the rubber mat is affixed to, which puts some distance between the iron platter and cartridge. Some have taken to increasing this distance by putting a second mat under the aluminum topper, or otherwise increasing the distance.

The TD124 MK 2 came with either the iron platter or the zinc composite platter that you are referring to. The Zamac platter, as the alloy is referred to, is not magnetically permeable at all and poses no issues to a MC. It is, however, somewhat lighter than the iron platter. I have a MK 2 and it is a nice turntable.

Thanks again, Viridian; looks like my restored TD 150 and 160 Super pass the  nonpermeability test, and I can continue interchanging my 4 LOMC cartridges between them.   

czarivey: I looked up  QRK   turntables, found it quite interesting. Thanks for your input.