So I finally got around to installing the Richard Freniac grip (see original post in thread.) Sorry it has been so long but I wanted to update the thread in case someone was looking into the grip.
Grip works great, installed easily. Took a little force to dislodge the OEM plastic grip. You can see a little scratch where my knife scratched the metal, but it was underneath the grip.
I "dry fitted" the new grip. The blue tape you see was put there to mark the position of the new grip so that I could more easily align the holes when I put the new grip on.
This is the grip installed, with my heaviest lens, a 24-70L MkI.
I don't normally plan on carrying my heavy L zooms with the EOS M but I thought I'd try it out with a lens that had some weight. The grip works great for my needs. Normally I use my EOS M with the 22mm or the EF adapter with one or two light zooms - usually the 40mm pancake and sometimes either my 35/2 or 85/1.8. In these situations, the grip adds just enough extra area to hold the camera, which makes it feel much more stable.
Just playing with the larger zooms I have, I find that you hold it by the lens anyway, so the extra grip is largely negated, because you would never hold the camera without supporting the lens. However, with smaller primes, which is how I usually shoot my M, it works great.
If anyone has any additional questions please ask me and I'll try to help answer!