Bit of an update:
Noticed a couple of new hairs along the front of my hairline, that were not there before. I generally only keep notice of this part as it's the most visable for me to see...Hopefully this means there is also new hair in other places like my crown, which I can't keep too close an eye on. My temples appear to be closing also, nothing amazing, but slow and steady new thin colourless hair appears, then turns dark in colour, although the new hair on the temples is still thin, as opposed to the new hair at the front which is terminal
Been using the derma roller for 3 1/2 months now 2x a week only, ocassionally I use emu oil with it as well, normally adding the emu oil once a week, and i'm a big fan of it, especially for a dry scalp.
All in all I definitely believe the derma roller works, just like the OP stated, and for me to be seeing new hair, although modest after 8 years of the big 3, is a very encouraging sign.
ps. I also use hair signals, 6 drops mixed with my minoxidil, for 18 months now, and I feel this also helps, and as it's only a few drops in my minoxidil it's no bother to me using it every day. I also only use minoxidil once a day...dropped from 2X about four years ago with no noticeable loss.