For enlarging purposes, a well-made roll-film holder is going to keep the film plane more precise than a tiny sheet film holder. Focus is fussier
as the format size diminishes - a lot less forgiving than when shooting 4x5. But I emphasize, well-made, when it comes to the choice of holder
itself. The camera also needs esp precise seating for the relevant holder. And with roll film you have the advantage of a wide selection of films and ease of loading. Regarding folders versus non-folder and monorails. ... folders are slower to use, simply because you have to unfold them and attach the lens etc. With a monorail you can leave a darkcloth on, even a favorite lens if needed. Some technical cameras will allow you keep keep a very small lens attached. But folders are generally more compact for travel. Another advantage to certain monorail
system is that if you need more bellows extension for a longer focal length, you simply add an extra rail section. I'm a long-lens addict myself.
Camera like 2x3 non-folding Ebonys are oriented more to wide-angle architectural work, and typically come equipped with a bag bellows.
I don't see anything inherently imprecise about 2x3" sheet film. It's on a thicker base than rollfilm and has no curl, so those are advantages, plus you have the advantage of individual control of development, if that's important to you.
Linhof rollfilm backs have excellent flatness, but they're also heavy and bulky. If you're shooting a lot of exposures, a rollfilm back is more compact, but for relatively few exposures, sheet film may be lighter or more compact.
For my 2x3" Technika, I have rollfilm backs, regular holders, and Grafmatics. Usually I use a higher speed rollfilm for handheld rangefinder shots, slower sheet film for shooting view-camera style on a tripod. I also use rollfilm for color.
All sheet film sags a little unless you have something like a vacuum back. Even lying flat, if you look at a reflection of something linear like a
fluorescent light bank, you can often spot a bit of waviness. More a problem with thin films and large film sizes - but the shorter focal distance of comparable perspective lenses with these smaller film sizes just makes it all fussier. I've also measured true focal plane positioning with even expensive view cameras using a specially built depth micrometer, and about all it takes is a tiny bubble in the varnish, or a little burr on diecast alum to make an issue. Ideally, one would not want to stop down a lens for this size film as far as with a 4x5. ... 6x9 is different enough to make a real difference, and 645 way down the food chain. Different strokes for different folks. But if you're going to the trouble of taking along filmholders, might as well make em 4x5 to begin with. 2x3 sheet film will be just as much fuss, and only a modest wt
savings. A properly made roll film holder will have no curl in the image area. A lot depends on one's expectations. My brother did a lot of
Tecknika 6x9 work back in the 60's, and only about half of it ever came out really sharp. I don't know how much of that was due to focus
issues, and how much due to less than ideal holders. I recently made a number of 16x24 enlargements of 6x9 Ektar roll film, which is pretty
insane by my own personal standards (I rarely enlarge more than 4X - and NO I don't need any comments from someone who tells me how they create inkjet smudges four feet from MF film!) and at that degree, any little glitch becomes a real problem visually. It's just hard to make small film resemble 4x5 work, let alone 8x10, but it's something I'm seriously experimenting with so that I can keep backpacking with
a view camera in old age. The days of lugging a 90 lb pack with a Sinar system in up the peaks and passes has ended. I'm not a fifty year old
teenager any more!
Brian, I'm coming late to this thread but I'm happy to recommend the Ebony "S" cameras. Although I use it exclusively for roll film I went for the 45S, for the following reasons:
1. More bellows freedom than the 23S. I wanted to use the 55/4.5 Apo-Grandagon lens and the 23S will not allow full use of the image circle because with rise, the top of the rear element of the lens hits the underside of the box which forms the rear standard. This box is bigger on the 45S, so allowing full rise with this lens.
2. Ability to see outside the 6x9 frame on the ground glass. I find this to be a great help when framing a picture.
3. Selling it on might be easier (I have no plans to do so!)
Of course the 23S is a bit smaller and lighter, and users of the Ebony 2x3 cameras really like the hinged back, which does away with the need to remove the focusing frame and find somewhere safe to put it (often in a hurry). However the Horseman roll film backs fit like a glove on the Ebony 5x4 cameras, and they are not that much bigger or heavier than the 6x9 backs.