I've been shooting with an Arca M-Line Two and a Phase 40+ back for almost a year now and am quite happy with it. I shoot mostly urban landscapes and architectural exteriors. I focus exclusively with the groundglass, carefully removing it out of doors and replacing it with the back. I can work quite quickly, as I worked with a 4x5 Sinar F (& F2) monorail camera outdoors for 25 years. I have six lenses from the 32mm Rodenstock to the 100mm Schneider apo-digitar. There are some issues. Focusing with wide angle lenses is often challenging, especially for lenses with apertures smaller than f/4. The Schneider 47 sometimes gives me trouble, and for some reason not clear to me, the Rodenstock 70mm HR. I also have a Rodenstock 40HR f/4 which is excellent and relatively easy to focus, and a 32mm Rodenstock HR which is more difficult to focus but doable. I use an 8x loupe. You really have to concentrate on focus because with wide angle lenses, the distance between infinity and one meter can be less than half a millimeter of movement along the standard. The gearing appears to be 20:1 but it would be much better at 30:1. Nevertheless I am losing only about 10-15% of images to bad focus, mostly with the lenses mentioned as sometimes problematic.
There is a second problem, albeit minor. I do a lot of stitching to create larger image files. And though the M-Line Two is very rigid, it is not perfect, as I presume a plate camera is. Stitched images will often have very small size difference where they overlap, on the order of 5 to 10 pixels out of 7300 or so. The images will also be slightly rotated away from each other. This means there is some small degree of play in the standards as they are shifted or raised or lowered. (For this reason do not even think about buying a film version view camera--the rigidity will definitely not be there either for consistent focusing or for accurate image stitching.)
It is trivial to make a small size correction in Photoshop (and the change really does not degrade the image) and a bigger pain to get the angle of rotation right to align the two images perfectly, but doing this allows me to make 80 megapixel files or bigger and increase the wide angle view of my images by one third or more.
Tilting and swinging the front standard is very easy and very effective, and yaw-free.
When everything works out right, the detail is very impressive, as is the colour rendition of the Rodenstock lenses, the Schneiders less so. The HR wide angle lenses have complex distortion which has to be corrected in software, such as Alpa's excellent LC program.
The whole system is very light compared to 4x5 film versions of the camera and quite a bit smaller. If you have the patience to work with a view camera and shoot a lot of architectural images or product photography, this is the way to go. For landscapes, there are other considerations such as vulnerability of the equipment to harsh conditions compared to closed cameras. But the quality of images can be excellent.