I have a related question: I want just a sturdy wrist strap or handgrip to attach on one side of my E-M5, maybe to one strap lug. (With a camera this light, I am happy to have it in one hand almost all the time, so my preferred "neck strap" is dropping the camera back into a camera bag.) Olympus has an accessory handgrip, but that needs the vertical grip, which I do not wish to burden myself with.
I do have a wrist-strap now, but it is a lightweight design intended for smaller cameras, so I would not trust it with a heavier lens like the 12-60/2.8-4 attached.
Are there good options? Do any of the systems discussed above cover this option?