I just did a search as I did not know about this camera. It may not be the best comparison to the Linhof. I could not find a direct description for the 6x12 model (I saw the 6x7/6x9 model, but I suspect the 6x12 is a 4x5 camera that takes a 6x12 back. BTW, Grimes is a machinist company for photographers that makes custom parts and sometimes cameras.
Horseman and Fotoman cameras would be a closer fit to the Linhof (or even a DAYI). You could also look at Silvestri, but that works better on a tripod. (The Gilde is a silly camera.) Fotoman 4x5 and the Cambo Wide are compact 4x5 cameras which would take a 6x12 back. Those are designed to be handheld.
I understand your frustration. 6x12 was never a very popular format. An actual 6x12 camera is rare, and except for the Chinese models, expensive. Going to a 4x5 with a 6x12 back adds unnecessary bulk to the system.
