I love Birkenstocks but this is my first pair of Madrids.  I must have missed wearing flip-flops because the sound is fun to me, even though keeping them on is a challenge because I like the straps buckled relatively loosely.  The Birk toe grip molded into the footbed makes it easier.  I also tend to mark up the inside upper of my shoes by hitting them with the sole of the opposite shoe when I walk and  so far the marks come right off  of the blk patent birko-flor with just a slight rub of a finger or soft cloth. I don't know if that's true with a lighter color or non patent.

Get yourself fitted properly because for some reason, nobody I know wears the American size that Birk translates to and an improper fit can exacerbate arch, knee and back problems.  Even though my feet grew a whole size as I got older, the same size  Birks I wore in my 20's work better for me.  I have a terrible time finding shoes wide enough for me (women's 7/12 E, used to be a 6 1/2 EE) and a 37 "Regular" width in a Birkenstock/Papillio/Birki's works for me. I'm always joking that Birkenstocks are for people who hate shoes.  With my high arch, wide foot, and stubby little toes I've always hated shoes, but not these  :)  When it is hot, this style is nice because there is not much touching the upper part of the foot.