Here's a link to a GetDPI thread summarizing my Horseman+ Hasselblad back experiences.
Horseman thread
In round terms the lens that you mount on the Horseman is going to be so demanding in terms of its goodness that focus and camera movement have got to be controlled carefully. There really aren't any good handheld solutions to the focus issue in the tech camera world. I used a tape. Others use laser rangefinders. Switching the back with a ground glass presents two issues: ground glass focusing isn't accurate enough for digital use (because of the ground glass's grain) and do you really want to make the switch in field conditions that are likely to produce good images. If you're considering a sliding back check out the videos on the Arca site on shimming to achieve accurate focus - and of course you still have the ground glass issue.
In actual use the tech camera (Horseman or otherwise) may not produce better results that your Hasselblad, which focuses accurately every time and is surprisingly hand holdable.
Which Hasselbad you have is important. On the Alpa website (which is informative and excellent) they recommend that backs with microlenses (such as the H4D-40) not be used with their cameras - I suspect that this applies to tech cameras in general.
My bottom line is that my H4D is my landscape camera. The kind of shooting that Siebel does demands a tech camera but general landscape work really doesn't.
Clearly, Woody, you are happy with how your Blad suits the way you shoot landscapes. This is great - and in line with my comments that you have to choose your equipment based on both how you shoot, and your image quality (IQ) expectations.
If I was happy with a reflex camera solution, as you are, I would be shooting landscapes with my Phase One and 28, 35, or 55 mm lenses, all of which sit in my bag. Alas, this solution does not meet my expectations. The reflex lenses from BOTH Phase and Hasselblad simply sannot match the quality of tech cam lenses. The optical compromises to lens design and performance caused by the presence of a mirror box mean the SLR lenses can't match the tech cam lenses for edge to edge sharpness, low distortion (both chromatic and curvature) or contrast.They do all that AND give you movements! Don't take my word for it, do your own tests.
My "general landscape photography" often utilises the advantages offered by my tech cam. I frequently use shift for perspective control, I sometimes shift and stitch etc. Have a look at the images on my profile here and you will see examples.
Importantly, the ALPA STC is substantially lighter than the reflex MF cameras, whatever your brand of choice. This means it is almost always with me. Yes, focus is a bit of a drag, but generally, with practice, this is easily overcome. I mostly use my "eye"ometer to focus. A good example is the shot of the snow-covered shoreline in my album on this site. The only thing sharp is the hanging ice. I estimated the focus. One of the great things about the ALPA is that when the focus ring says 0.7 meters, that is where the point of focus is. (The new precision focussing ring they are offering is a major help in this regard and is the must-have item for Alpa owners). That was certainly NOT the case with my Horseman SW-DII.
Woody is absolutely correct in his assertion that a groundglass is not a viable solution. The problem is not only the grain on the screen (The ALPA screen is very fine grained), but also that with wides and ultra wides, the light is striking the lens is at such an obtuse angle that even the best fresnel screen cannot bend it towards your eye or magnifier well enough for clear viewing. Thus you can only effectively focus the centre of the image. Once you are out to focal lengths of around 60mm or more, this is less of an issue, unless using extreme shifts. Remember also that as your focal length decreases, so too does your depth of focus (think of it as DOField in the image plane, not the subject plane). This is why ALPA insist on shimming to 100ths of a milimeter. Manufacturing tollerances with groundglass systems mean that getting a precise correlation between your groundglass and back is nearly impossible with wide lenses. Sliding groundglass systems add yet another layer of inaccuracy due to the tollerances required for the rail to move. This is one of the reasons I shoot tethered whenever possible.
The microlens issue needs to be taken with a grain of salt. Earlier microlensed sensors such as the one in the P30+ throw can throw major colour casts that are beyond the capability of the software LCC (lens cast correction) to correct. Note that this is variable from back to back and some P30+ users are using their backs successfully, so I hear. The 40 and 60MP sensors from Dalsa, as found in the current Phase and Hasselblad backs are also microlensed, but use a different method that reduces the amount of colour cast. This is usually correctable easily by software LCC. I shoot with P40+, P45+ and P65+ backs daily and have only seen casts (after LCC) appear when I massively tweak the curves to exaggerate local contrast.
There is a striping artefact that can sometimes appear with ultra wides or when using extreme shifts. It can be seen in areas of smooth tones in lighter areas. There is no solution currently to this problem. The HR Digarons are less prone to this as their semi retrofocal design means they deliver light to the sensor at a less severe angle than the symmetrical lens designs (such as the Schneiders).
Bottom line is tech cams are capable of vastly superior IQ edge to edge than any Reflex camera, but this comes at the price of some focussing issues. Lets be clear that despite the drawbacks I've just discussed, tech cams offer major advantages in IQ and portability as well as the obvious advantage offered by camera movements.
Once again, test lots, read widely, be careful of uninformed information passed off as fact on websites (I am not referring to you Woody, I'm generalising) and choose the camera that suits your style, methods of working, IQ expectations and type of photography. Then apply the most important data filter - the "fit to budget" filter. In my case, this is called Mrs.Siebel, also known in some circles as "The Finance Minister".
Remember to relax. This is supposed to be FUN!
Happy shooting!
Cheers,