I know that the Millie series has been designed with one focus of making them easily cleanable, and that a backspacer kind of defies this purpose. I have installed low cost backspacers to my Para 3 and PM2 anyway because I like the looks. After all I'd probably use a different spydie if I ever had to use them in the dirt - probably my Pacific Salt.
I now looked for a backspacer for my Millie - but only found a small handful of offers on the bay (where I look for such things usually).
Anyone have a clue why there are tons of backspacers for the PM2, some for the Para 3, but next to none for the Millie? I doubt that it is out of respect for Sal's initial design idea. I don't get it...