December 20, 2015
I got this strap a few days ago, and it works perfectly. Especially when mounting the 40-150mm Pro lens to the E-M1 and HLD-7 battery grip. It fits around my hand comfortably, and you can adjust it for a snugger or looser fit as desired.
When shooting in vertical format, I leave my hand in the grip and use the standard shutter button, but I have slipped my hand out of the grip to hold the camera by the HLD-7 base, which gives good access to the function buttons. Holding the camera this way still works well for vertical shots.
The GS-5 strap works well for me. Don't tighten it too tight on your hand... You may need just a little slack, to allow your hand to reach different buttons, etc.