I have also just come across these posts and read the comments about the 'Red Caps' with interest.
I was a VT from the infantry and served in 180 Pro Coy RMP from 74 to 76, based at Aldergrove. I too wore the SD cap until mid 75 when we changed to our bright red beret. I loved my SD cap but like most hated putting the creases into the red cotton cap cover, but boy, did it look good when done and I was and am still proud to have worn one. My cap badge was, I'm also proud to say, was a brass RMP badge, not staybright.