I've been using a Techno for a couple of years now - with lenses from 28 to 120 - without a hitch.
To nail focus I use an 8x lupe, and have never had a problem focussing
, even with the 28mm (which more often than not is simply shot at its HFD@f8, which I have marked the position of). I don't use an IQ back - which would make nailing focussing even easier I would imagine, since it has that great screen/zoom/focus-mask ability.
It does seem like the Techno may be stuck in the very very small niche for those that can afford a digital back but not the expensive lens systems of Arca R-Line and Alpa.
Sorry, but from my perspective as a working professional that's just plain wrong. Given the total $ investment I have in photographic equipment, the cost of the mounts is (relatively) inconsequential. Don't misunderstand me, money is just as much an issue for me as the next guy, but over the working life of the equipment - which will (hopefully) be many jobs over many years - this extra cost can be easily absorbed. For me the Techno was the best tool for my
kind of work, and that's the absolute bottom line as to why I chose it. It's at home in the studio (shooting products/still-life/macro) and on location (shooting food/architecture/landscape), with lenses from 23 - 250, and simultaneous (yaw-free) swing/tilt available on every lens. In addition, by combining front rise/fall/shift with rear fall/rise/shift you can cover the entire image circle of pretty much any lens (designed for digital) out there.
From the comments so far it seems like it indeed works ok, but there are some limitations with the GG. Wide angles are darker, especially in the corners and at some point it will become almost impossible to focus. Say if a 35mm only can be focused in full daylight and then only in the center of the picture, that would feel very limiting for me.
A 'one ground-gless fits all' approach is always going to have limitations. I have two fresnel-based ground-glasses with different focal lengths - one for my wide-angles, one for longer lenses.
Even if the Techno works it is so much uncertainty around it that you'd choose Arca/Alpa if you can.
'So much uncertainty' - again, that's simply nonsensical. The only uncertainty I can see is whether or not you've actually used this camera?