Leica makes 15x LRF binos. My buddy has them, and obviously they can only range off a tripod. I don't know of anyone making them in 12x. I don't think anyone will, but maybe I could be wrong.
When it comes to practicality, you have to use 12x and 15x binos on a tripod or supported if they have a rangefinder. I ran 12X binos for years and a 7x RF. My system before was Leica Ultravid 12X bino and a 7x RF. Now, I run the 10x Fury and 18X Razor. When I get some extra funds, I'll probably upgrade to some better 15X bino.
I first switched to the 10X Sig 3000bdx and now the Fury AB. Hand holding 10x is harder than the lighter dedicated RF because weight matters at that scale. I made this switch because when doing my quick glassing in an area, or watching feeding/moving animals, I didn't want to switch to the RF. If you have ever been watching Coues whitetail, you can lose them in a blink. Also, I like to pull out my optics quite often to get a look at something, and part of my practice is to guess the distance, and then range it. Helps me calibrate my eyeballs and get a sense for what is shootable from wherever I am glassing.
That is my reason to switch, to have the RF in my bino so I didn't have to futz around with multiple optics as much. But, I had to add in a bigger bino to pick apart the hillside, which I could do with my Leica Ultravids. There is a noticeable difference. And, it took me over a year to finally sell my Leica because I was indecisive about my glass set up.
I don't think I would use 12x or 15x rangefinding bino. At best, I could handhold my 12x bino for a quick scan, but if I wanted to catch detail, I had to go to my tripod. Of course, I am talking picking apart bushes and scrub looking for the flick of a deer ear. I wouldn't want to try to range find with 12x because of that, I would always have to go to a tripod. I can get away with it using my 10x, because the weight makes the 10x a little easier to handhold and range.
The ones I am running are passable, but I still wonder if leaving my 12X Ultravid Leica and the handheld RF was better. I could run that pretty much everywhere and add in a Kowa 554 and be at or near the same weight. Its a toss up in my eyes whether the extra clarity of the 12x I gave up is worth the extra magnification of the 18x.
