Hi.

But, McD's fries have always been processed potato. The same as pretty much any other frozen fry. It is not a slice of potato by any stretch of the imagination.

Oh well, while I know I had some fries at McD in Denver (don't remember the exact place) that where definitely made from potatoe mash, I know for sure (i.e. 100%) that the ones they use in Germany are _not_ made from potatoe mash. The kind of potatoe they use, however, is a soft cooking type (correct expression?) i.e. if cooked/fried just a bit too long, they turn into a very soft consistency inside, almost to mash. The reason I know this is that (1st) they would have to explicitly state on the menu that they using "fake" fries if they did and (2nd) I know where they buy their deep frozen pre-cooked fries and visited the factory that produces them.
Different countries however have different rules, so I won't guarantee this for any other country.
As for the BK subject: Other than McD, BK seems to have extremely varying quality levels from country to country (and possibly even within one country). I have been to some BKs that where bad that I returned the complete meal after the first bite, but our local BK is that good, that I actually would compare it's whopper to a home made Burger (though not to a real good one). I would never even think twice about doing so with any Burger McD has ever sold.

cu,
sven