I missed this the first time around. I used to have a Yashica MAT 124 G and I loved it. Part of that was it was my first MF camera. Boy did I love those big negatives. That kept me from thinking too much about the fact that if I was going to print in rectangle, I wasn't getting the full 6x6, but even 645 was bigger than 35mm. The weight didn't bother me so much then as I still had a strong back to go with my weak mind. I would carry it and a 35mm kit around the mountains of Korean and was happy.
After I got the Mamiya Super Press 23, and found an even larger rectanglular negative, I haven't been able to enjoy a 6x6 again.
That said, you do get used to the reversed image. Or at least I did and most if not all people do. There is also the not much needed advantage that it can be held overhead to get around obstacles such as fences or people at parades. As I said, not much needed, but like a seldom used tool, nothing better when you do need it. I found the meter on mine to be spot on, but like any other cameras, you may find a stop difference between any two. I think that was never common, and perhaps even less common these days, but twenty to twentfive years ago, was accepted as an undesireable but acceptable possibility.
Have you developed any negatives from the 124 Mat? Have you changed you feelings about it? Of course, I realize this thread was before the heart episode, but I would be interested to hear your thoughts now. Unfortunate about straps bothering you. Is there any chance it was related to your health issue and that it might not bother you now? If no change, then a wider strap probably isn't going to help. I know a wide strap helps a lot with my Mamiya. It doesn't seem very heavy at all with a wide Yashica strap on it. Or maybe it is just that is is a Yashica strap? 😀
How about an update Joe?